1、17/17特殊疑問(wèn)句練習(xí)題（一）一、選擇正確的單詞填空(who, where, when)1._ is that pretty girl? She is my sister.2._ are Jack and Tom? They are behind you.3._ do you go to school? I go to school from Monday to Friday.4._ has a beautiful flower? John has a beautiful flower.5._ are they? They are my parents.6._ is my mother? S

2、he is in the living room.7._ are you going? We are going to the bakery(面包坊).8._ do Jim and Wendy play ball? They play ball in the afternoon.9._ does he jog? He jogs in the park.10._ are you from? Im from Changchun city.二、就畫(huà)線(xiàn)部分提問(wèn)1.He is my father.2.They are under the tree.3.I often watch TV after din

3、ner.(晚飯后)提示：飯后強(qiáng)調(diào)的是時(shí)間問(wèn)題。4.Lily swims in the swimming pool.(游泳池)5.Superman flies in the sky.6.I often brush my teeth in the evening.7.Alan likes to play with Bill.8.Joes father plays badminton(羽毛球) every weekend.9.The supermarket is near the school.10.The laptop(筆記本電腦) is on the table.11.Jennifer has

4、a pair of earrings(耳環(huán)).12.The flowers are in the flower pot(花盆).13.My grandpa took us to the zoo.14.I put the gold fish(金魚(yú)) into the fish tank(魚(yú)缸).15.Themonkey sleeps at night. 特殊疑問(wèn)句練習(xí)（二）一用what time, what color, what day,what填空。1. A: _ _ is it? B: It is nine oclock.2. A: _ _ does your mother get up?

5、 B: My mother gets up at 6:30.3. A: _ _ do you go to bed? B: I go to bed at 10:00.4. A: _ _ do Diana and Fiona have supper? B: Diana and Fiona have supper at 18:00.5. A: _ _is it? B: It is purple.6. A: _ _ is the sky? B: The sky is blue.7. A: _ _ is your coat? B: My coat is black.8. A: _ _ is the do

6、g? B: The dog is white.9. A: _ _ is today? B: Today is Monday.10. A: _ _ is tomorrow? B: Tomorrow is Tuesday.11. A: _ _ was yesterday(昨天)? B: Yesterday was Sunday.12. A: _ _ do you like? B: I like red.13. A: _ is this? This is a computer(電腦).14. A: _ are you doing? B: We are playing basketball.15. A

7、: _ does your mother do? B: My mother is a policewoman.16. A: _ are those? B: Those are peppers(辣椒).17. A: _ is in the box? B: A lovely doll is in the box.18. A: _ is on the table? B: The apple is on the table.19. A: _ is in the classroom? The blackboard is in the classroom.20. A: _ _ _? B: Mary is

8、hungry.21. A: _ _ _ _ _? B: My favorite color is pink.22. A: _ _ _ _? B: Nick is playing table tennis.二連線(xiàn)：（Match）1. Whats on the chair?There is a book in the bag.2. How is your father?These are apples.3. What are these?I go to school by bus.4. What is in the bag?The radio is on the chair.5. How do y

9、ou go to school? My father is fine.6. How much is it?I wash my face in the morning.7. What time is it?I have two hands.8. When do you wash your face? It is four oclock.9. How many hands do you have? It is 5 RMB(人民幣).10.When do you have lunch? I have lunch at noon.一、詞類(lèi)：動(dòng)詞、名詞和形容詞不太容易區(qū)分，如不能一眼看出，可用如下方法：

10、先用“一（量詞）”（如：一個(gè)、一張等）和這個(gè)詞連起來(lái)說(shuō)，如說(shuō)得通，一般認(rèn)為是名詞；說(shuō)不通再用“很”去判斷，就是把“很”和為個(gè)詞連起來(lái)說(shuō)，說(shuō)得通一般就是形容詞；都說(shuō)不通就是動(dòng)詞。（目前我們學(xué)過(guò)的，以后可能不同）（另外一些很明顯的，如人稱(chēng)代詞、數(shù)詞、情態(tài)動(dòng)詞等一下就可以知道）動(dòng)詞這里所說(shuō)的動(dòng)詞是指各種動(dòng)詞總稱(chēng)，其中包括行為動(dòng)詞（就是我們平時(shí)總說(shuō)的那種動(dòng)詞）、be動(dòng)詞、情態(tài)動(dòng)詞。（1）行為動(dòng)詞就是我們平時(shí)上課時(shí)說(shuō)的動(dòng)詞，表示某一動(dòng)作或行為。如：sweep、live等。行為動(dòng)詞我們已學(xué)過(guò)它們的四種形式：原形、+s/es、+ed、+ing，具體判斷方法如下：有，就加ing讀句子讀該單詞認(rèn)識(shí)該單詞理解意思

11、看有無(wú)be動(dòng)詞（若是be going to 就用原形）沒(méi)有，再看情態(tài)動(dòng)詞有，就用原形有，就加ed沒(méi)有，再看有無(wú)表示過(guò)去的時(shí)間狀語(yǔ) 是第三人稱(chēng)單數(shù)就加s或es 沒(méi)有，再看主語(yǔ)不是第三人稱(chēng)單數(shù)就用原形（2）be動(dòng)詞a、Am-was Is -was Are-were 口訣：我用am, 你用are, is用在他她它，所有復(fù)數(shù)全用are。b、肯定和否定句 I am (not) from London. He is(not) a teacher. She is(not) in the dining room. My hair is(not) long. Her eyes are(not) small. c

12、、 一般疑問(wèn)句 Am I a Chinese? Yes, you are. No, you arent. Are they American? Yes, they are. No, they arent. Is the cat fat? Yes, it is. No, it isnt. 我們現(xiàn)在學(xué)過(guò)的be動(dòng)詞大致分兩類(lèi)：is、am、are為一類(lèi)，一般用于一般現(xiàn)在時(shí)、現(xiàn)在進(jìn)行時(shí)和一般將來(lái)時(shí)中，was和were為另一類(lèi)，一般用于一般過(guò)去時(shí)。判斷步驟： 第一、三人稱(chēng)單數(shù)，就用was有，再看人稱(chēng)第二人稱(chēng)單數(shù)和所有復(fù)數(shù)，就用were看有無(wú)表示過(guò)去的時(shí)間狀語(yǔ)第一人稱(chēng)單數(shù)，就用am沒(méi)有，再看人稱(chēng)第三人稱(chēng)單數(shù)

13、，就有is第二人稱(chēng)單數(shù)和所有復(fù)數(shù)，就用are（3）情態(tài)動(dòng)詞情態(tài)動(dòng)詞也是一類(lèi)特殊的動(dòng)詞，平時(shí)我們不把它說(shuō)成是動(dòng)詞。情態(tài)動(dòng)詞可以和行為動(dòng)詞同時(shí)出現(xiàn)在同一個(gè)句子中。我們現(xiàn)在學(xué)過(guò)的情態(tài)動(dòng)詞有：can、must、should、would、may。接觸最多的是can。情態(tài)動(dòng)詞后動(dòng)詞總是用原形。（不受其他任何條件影響）名詞表示某一事物，有具體的和抽象的之分。判斷的關(guān)鍵詞往往是be動(dòng)詞，be動(dòng)詞如果是am、is或was，名詞就用原形；be動(dòng)詞如果是are或were，名詞就加s或es。這里強(qiáng)調(diào)兩點(diǎn)：不可數(shù)名詞都默認(rèn)為單數(shù)，所以總是用is或者was；最好不要根據(jù)some、any、a lot of等詞去作判斷，以免

14、受誤導(dǎo)。如何加后綴：a一般情況下，直接加-s，如：book-books, bag-bags, cat-cats, bed-beds b以s. x. sh. ch結(jié)尾，加-es，如：bus-buses, box-boxes, brush-brushes, watch-watches c以“輔音字母+y”結(jié)尾，變y為i, 再加-es，如：family-families, strawberry-strawberries d以“f或fe”結(jié)尾，變f或fe為v, 再加-es，如：knife-knives e不規(guī)則名詞復(fù)數(shù)： man-men, woman-women, policeman-policeme

15、n, policewoman-policewomen, mouse-mice child-children foot-feet,.tooth-teeth fish-fish, people-people, Chinese-Chinese, Japanese-Japanese 判斷步驟： 如是am、is或was原形讀句子讀該單詞認(rèn)識(shí)該單詞理解意思看be動(dòng)詞如是are或were加s或es形容詞（包括副詞）形容詞表示某一事物或的特征，副詞表示某一動(dòng)作的特征。形容詞和副詞只有兩種形式：原形和+er。未作比較的情況下就用原形，比較時(shí)就+er。兩個(gè)重要特征：asas中間一定用原形，有than的時(shí)候一定+e

16、r。人稱(chēng)代詞和物主代詞人稱(chēng)代詞物主代詞單數(shù)復(fù)數(shù)單數(shù)復(fù)數(shù)主格賓格主格賓格形容詞性（短）名詞性（長(zhǎng)）形容詞性（短）名詞性（長(zhǎng)）第一人稱(chēng)Imeweusmymineourours第二人稱(chēng)youyouyouyouyouryoursyouryours第三人稱(chēng)hehimtheythemhishistheirtheirssheherherhersitititsits人稱(chēng)代詞：有主格和賓格之分。一般動(dòng)詞前用主格，動(dòng)詞后用賓格。物主代詞：有兩類(lèi)：形容詞性物主代詞（短的）和名詞性物主代詞（長(zhǎng)的）一般看后面有沒(méi)有名詞，如有，就用形容詞性物主代詞（短的）；如無(wú)，就用名詞性物主代詞（長(zhǎng)的）。數(shù)量詞我們學(xué)過(guò)兩類(lèi)：基數(shù)詞和序

17、數(shù)詞?；鶖?shù)用于表示數(shù)量多少，而基數(shù)詞用于表示次序，常在日期中出現(xiàn)。6、冠詞有a、an、the。a和an有具體的意思，一（個(gè)），the沒(méi)有具體意思，有時(shí)翻譯為這、那。確定用a、an還是the時(shí)可根據(jù)漢語(yǔ)意思。a和an的區(qū)別：an用于元音音素（一般就是元音字母aeiou）前，a用于輔音音素前。二、否定句：表示某一否定意思。句中一定有not。有三種可能：be動(dòng)詞（am、is、are、was、were）+not、情態(tài)動(dòng)詞（can、must、should）+ not、助動(dòng)詞（do、does、did） + not如何將一個(gè)肯定的陳述句改為否定句：1、看句中有無(wú)be動(dòng)詞，如有，直接在be動(dòng)詞后+ not。2

18、、看句中有無(wú)情態(tài)動(dòng)詞，如有，直接在情態(tài)動(dòng)詞后+ not。3、如上述二者都沒(méi)有，就應(yīng)用助動(dòng)詞+ not。分四個(gè)步驟：（1）肯定陳述句中本來(lái)是沒(méi)有助動(dòng)詞的，要加上去，位置在主語(yǔ)（某人/某物）后，動(dòng)詞前。（2）確定助動(dòng)詞用do、does還是did，根據(jù)句中動(dòng)詞，動(dòng)詞是原形的助動(dòng)詞就用do，動(dòng)詞是第三人稱(chēng)單數(shù)的助動(dòng)詞就用does，動(dòng)詞用過(guò)去式的助動(dòng)詞就有did。（3）在助動(dòng)詞后加not。（4）原句中動(dòng)詞假如發(fā)生變化就要恢復(fù)成原形。強(qiáng)調(diào)一點(diǎn)，有some的要考慮是否要用any。三、一般疑問(wèn)句。表示疑問(wèn)，一般回答只有兩種可能Yes，或No，句中沒(méi)有疑問(wèn)詞。如何將一個(gè)肯定的陳述句改為否定句：1、看句中有無(wú)be

19、動(dòng)詞，如有，把be動(dòng)詞提到句首即可。2、看句中有無(wú)情態(tài)動(dòng)詞，如有，把情態(tài)動(dòng)詞提到句首即可。3、如上述二者都沒(méi)有，就應(yīng)把助動(dòng)提到句首。分四個(gè)步驟：（1）肯定陳述句中本來(lái)是沒(méi)有助動(dòng)詞的，要加上去，位置在主語(yǔ)（某人/某物）后，動(dòng)詞前。（2）確定助動(dòng)詞用do、does還是did，根據(jù)句中動(dòng)詞，動(dòng)詞是原形的助動(dòng)詞就用do，動(dòng)詞是第三人稱(chēng)單數(shù)的助動(dòng)詞就用does，動(dòng)詞用過(guò)去式的助動(dòng)詞就有did。（3）把助動(dòng)詞后提到句首。（4）原句中動(dòng)詞假如發(fā)生變化就要恢復(fù)成原形。強(qiáng)調(diào)一點(diǎn)，有some的要考慮是否要用any。四、特殊疑問(wèn)句。表示疑問(wèn)，有疑問(wèn)詞（在開(kāi)頭），回答有很多種可能。常用疑問(wèn)詞：What、When、Wh

20、ich、Who、Whose、Why、How如何對(duì)劃線(xiàn)部分提問(wèn)：1、將原問(wèn)句翻譯為漢語(yǔ)（在讀中要將劃線(xiàn)部分重讀）。如：His birthday is on the 5th of May . 他的生日在五月五日。2、用漢語(yǔ)進(jìn)行提問(wèn)。如上句，應(yīng)該問(wèn)：他的生日在什么時(shí)候？3、根據(jù)漢語(yǔ)將所要提問(wèn)的句子補(bǔ)充完整。如上句When is his birthday ?五、祈使句表示請(qǐng)求或命令別人做某事或不要做某事?？隙ㄆ硎咕湟欢ㄊ且詣?dòng)詞原形開(kāi)頭（有時(shí)有please），否定的祈使句一定是dont加動(dòng)詞原形開(kāi)頭（有時(shí)有please）。把祈使句改為否定句只需在動(dòng)詞前加dont即可。六、時(shí)態(tài)1、一般現(xiàn)在時(shí)（1）句中be

21、動(dòng)詞和動(dòng)詞一般情況下只能有一種而且也必須有一種。如：The children are very happy on Christmas Day .She often does some housework at the weekend .（2）一般現(xiàn)在時(shí)中的be動(dòng)詞：一般用原形：am is are am用于第一人稱(chēng)單數(shù)（I）；is用于第三人稱(chēng)單數(shù)（he she it和其他人名或稱(chēng)謂，如：Ben his sister等）；are用于第二人稱(chēng)單數(shù)（you）和所有復(fù)數(shù)（包括第一人稱(chēng)復(fù)數(shù)we、第二人稱(chēng)復(fù)數(shù)you；第三人稱(chēng)復(fù)數(shù)they和其他復(fù)數(shù)，如the children 、 his parents等）。

22、（3）一般過(guò)去時(shí)中的動(dòng)詞：有兩種情況：第一種情況：主語(yǔ)是第三人稱(chēng)單數(shù)（he she it 和其他，如Helen 、her cousin 等），動(dòng)詞后一般加s或es。第二種情況：主語(yǔ)不是第三人稱(chēng)單數(shù)，動(dòng)詞都用原形。（4）一般現(xiàn)在時(shí)判斷依據(jù)（如何判斷一個(gè)句子是一般現(xiàn)在時(shí)）：be動(dòng)詞是am、is、are動(dòng)詞用原形或加s、es沒(méi)有時(shí)間狀語(yǔ)或有usually、often、everyday、sometimes等不是具體的時(shí)間（5）有用的的依據(jù)：Be動(dòng)詞是is、am 名詞用原形（這里包括可數(shù)名詞的單數(shù)和不可數(shù)名詞）Be動(dòng)詞是are 名詞加s或es動(dòng)詞加s或es 主語(yǔ)是第三人稱(chēng)單數(shù)動(dòng)詞用原形 主語(yǔ)不是第三人稱(chēng)

23、單數(shù)（6）情態(tài)動(dòng)詞：我們現(xiàn)在學(xué)過(guò)的情態(tài)動(dòng)詞有：can、must、should、would。情態(tài)動(dòng)詞后動(dòng)詞總是用原形。（不受其他任何條件影響）2、一般過(guò)去時(shí)（1）句中be動(dòng)詞和動(dòng)詞一般情況下只能有一種而且也必須有一種。如：The girls were on the grass just now .They visited my parents last weekend .（2）一般過(guò)去時(shí)中的be動(dòng)詞：一般用過(guò)去式：was were was用于第一人稱(chēng)單數(shù)（I）和第三人稱(chēng)單數(shù)（he she it和其他人名或稱(chēng)謂，如：Ben 、 his sister等）；were用于第二人稱(chēng)單數(shù)（you）和所有復(fù)數(shù)

24、（包括第一人稱(chēng)復(fù)數(shù)we、第二人稱(chēng)復(fù)數(shù)you；第三人稱(chēng)復(fù)數(shù)they和其他復(fù)數(shù)，如the children 、 his parents等）。（3）一般過(guò)去時(shí)中的動(dòng)詞：一般只有一種情況：+ed這里強(qiáng)調(diào)一點(diǎn)，和一般現(xiàn)在時(shí)不同的是這里不管主語(yǔ)是第幾人稱(chēng)，也不管是單數(shù)和復(fù)數(shù)都加ed。（4）一般過(guò)去時(shí)判斷依據(jù)（如何判斷一個(gè)句子是一般過(guò)去時(shí)）：be動(dòng)詞是was、were動(dòng)詞加ed有表示過(guò)去的時(shí)間狀語(yǔ)現(xiàn)在學(xué)過(guò)的常用的表示過(guò)去的時(shí)間狀語(yǔ)有：just now ， a moment ， yesterday ， last week ， last night， last weekend ， last year ， las

25、t month ， three days ago ， two weeks ago ， five years ago（5）有用的的依據(jù)：Be動(dòng)詞是was或were 該句是一般過(guò)去時(shí)動(dòng)詞加ed 有表示過(guò)去的時(shí)間狀語(yǔ)3、一般將來(lái)時(shí)（1）構(gòu)成形式：Be going to +動(dòng)詞原形。這里強(qiáng)調(diào)一點(diǎn)，be動(dòng)詞、going、to以與動(dòng)詞原形共四個(gè)單詞缺少其中任何一種都不可以構(gòu)成一般將來(lái)時(shí)。（2）一般將來(lái)時(shí)表示動(dòng)作即將發(fā)生或某人打算做某事。（3）有用的依據(jù)：一個(gè)句子中既有be動(dòng)詞，又有g(shù)oing、to和動(dòng)詞，且動(dòng)詞用的是原形 該句是現(xiàn)在進(jìn)行時(shí)（4）句中往往有tomorrow、soon、next week等詞。

26、4、現(xiàn)在進(jìn)行時(shí)（1）構(gòu)成形式：Be動(dòng)詞+動(dòng)詞的ing形式這里強(qiáng)調(diào)一點(diǎn)，兩者缺少其中任何一種都不可以構(gòu)成現(xiàn)在進(jìn)行時(shí)。（2）現(xiàn)在進(jìn)行時(shí)表示動(dòng)作正在進(jìn)行或事情正在發(fā)生。（3）有用的依據(jù)：一個(gè)句子中既有be動(dòng)詞，又有動(dòng)詞，且動(dòng)詞加了ing 該句是現(xiàn)在進(jìn)行時(shí)（4）句中往往有now、look、listen等詞。七、Have、Has和There be結(jié)構(gòu)1、There be結(jié)構(gòu)包括there is there are there was there were2、意思都是“有”。3、和have、has、had的區(qū)別：（1）There be 句型表示：在某地有某物（或人） （2）在there be 句型中，主語(yǔ)

27、是單數(shù)，be 動(dòng)詞用is ; 主語(yǔ)是復(fù)數(shù)，be 動(dòng)詞用are ; 如有幾件物品，be 動(dòng)詞根據(jù)最近be 動(dòng)詞的那個(gè)名詞決定。 （3）there be 句型的否定句在be 動(dòng)詞后加not , 一般疑問(wèn)句把be 動(dòng)詞調(diào)到句首。 （4）there be句型與have(has) 的區(qū)別：there be 表示在某地有某物（或人）；have(has) 表示某人擁有某物。 （5）some 和any 在there be 句型中的運(yùn)用：some 用于肯定句，any 用于否定句或疑問(wèn)句。 （6）and 和or 在there be句型中的運(yùn)用：and 用于肯定句， or 用于否定句或疑問(wèn)句。（7）針對(duì)數(shù)量提問(wèn)的特

28、殊疑問(wèn)句的基本結(jié)構(gòu)是： How many + 名詞復(fù)數(shù) + are there + 介詞短語(yǔ)？ How much + 不可數(shù)名詞 + is there + 介詞短語(yǔ)？ （8）針對(duì)主語(yǔ)提問(wèn)的特殊疑問(wèn)句的基本結(jié)構(gòu)是： Whats + 介詞短語(yǔ)？ （9）There be結(jié)構(gòu)一般用在句子的開(kāi)頭，而have等詞只能用于某一個(gè)主語(yǔ)后面。四年級(jí)英語(yǔ)上句型練習(xí)題一、 讀一讀，想一想，把句子與其對(duì)應(yīng)的中文意思連起來(lái)。1. Is she in the study? 它們?cè)谧雷由蠁幔?. Are they on the table? 她在書(shū)房嗎？3. Is Mike in the kitchen? 你想吃點(diǎn)什么？4

29、. What would you like? 邁克是在廚房嗎？5. Whats for dinner? 我能要一些湯嗎？6. Can I have some soup? 晚餐有些什么？7. I am hungry. 我可以幫忙嗎？8. Can I help you？我餓了。9. I like chicken. 你喜歡牛奶嗎？10. Do you like milk? 我喜歡雞肉。二、讀一讀，辨一辨，為下列答句選擇正確的問(wèn)句。（）1. Id like some fish, please. A. What can you see in the room? ( ) 2. Yes, please. B

30、. Where is the chicken? ( ) 3. Yes, I do. C. What would you like? ( ) 4. Yes, here you are. D. Whats for dinner? ( ) 5. No, they arent. E. Can I help you? ( ) 6. Soup and fish. F. Can I have some fish? ( ) 7. Yes, she is. G. Do you like milk? ( ) 8. No, he isnt. H. Is he in the kitchen? ( ) 9. Its o

31、n the plate. I. Is she in the study? ( )10. I can see a window, a bed and a desk. J. Are they on the table?三、讀一讀，把對(duì)話(huà)補(bǔ)充完整，選擇正確問(wèn)句的編號(hào)填在相應(yīng)的橫線(xiàn)上。A. Mom, _B. A. Everythings ready.B. Can I have some soup?C. Can I help you?D. Whats for dinner?E. What would you like?Yes, pass me a plate.A: Ok! _B: Some vegeta

32、bles and beef.A: Great! _B: Sure. _A: Id like some fish soup.B: _A:Thank you, Mom!四、連詞成句。1. am, I , hungry. 2. soup, Id , some, like. 3. on, the , its , plate. 4. door, in , theyre, the. 5. like, I , chicken. 6. dinner, whats, for? 7. I, can, you, help? 8. would, what, like, you? 9. is, the , key, w

33、here? 10. can, see, what, you? 英語(yǔ)音標(biāo)與字母組合對(duì)照1.元音:1) i: 字母組合:ee ea e ie ei （eoeyi）three tree green sheep meet beef see seek eat tea meat leave lead teacher team mean speak clean pleasehe she me piece receive ceiling 2) I 發(fā)音字母 i y euiuasit picture it is list six mix fix fit pig big build missmyth many t

34、wenty happy dictionarydefect decide delicious 3) 發(fā)音字母 abag hand and ant happy hat map mad bad black back glad flag shall man 4) e 字母組合 ea e a （ue,u,ie,ai,ei,ay）head bread pleasureelephant electric remember sell shell lesson better bed desk hotel yesmany any 5) : 字母組合ir ur ear er orgirl shirt skirt t

35、hirty thirteen third bird turn burn murder nurse turtle Thursday burgerlearn earn earth heardterm her nerd servework worm work world 6) 字母組合 er or ou ar o a e uteacher leader remember player speaker farmer powderdoctor actor mayor author tractordelicious gracious pleasure familiar collar dollar toge

36、ther tomorrow today shallop lesson Washington control polite around account ago elephant manta banana Canada Japan chinamen listen famulus Saturday 7) a: 字母組合 ar acar farm card arm gardenfast class last glass plant aunt calm 8) 發(fā)音字母 u o ou oo up supper lunch fun gun hunt cup buscome mother dose brot

37、her love above trouble rough flourishblood flood9) :字母組合 al or au our arsmall wall talk tall hall ball call walk short more lord horse for forty sport door floor store author caught autumnfour mourn court bought warm quarrel quarter 10) ()發(fā)音字母 o aouhot lost lot fox box mop hop loss collar notwant wash watch 11) u: 字母組合 oo o ufood moon room gloom broom doom goose toothshoe do twotrue truth blue full prude12) u 字母組合 oo ou u olook good foot book wood should could put full bull pull pushwoman wolf 13) ei 發(fā)音字母 a ay ea ai