五、 連詞
(一) 知識概要
連詞是一種在句子與句子之間，短語之間以及名詞等其他詞語之間起連接作用的虛詞，它不能單獨作句子的成份。按其意義可分為并列連詞和從屬連詞兩大類。 并 列連詞連接的雙方是對等的。常有的并列連詞有and, both…and, either…or, neither…nor, not only…but also, as well as等。但如果連接的兩部分意義不趨向一致，意義有轉(zhuǎn)折的并列連詞有：but, however, while (而)，only (只不過)。還有表示選擇關(guān)系的并列連詞，如：or, or else, otherwise… 再有的是連接雙方，互為因果，或表示前因后果的連詞有：for, so, therefore (因此)，then等。 從屬連詞在初中范圍內(nèi)常常用來連接名詞性從句，如：that, if, whether, 其次用來連接狀語從句。其中有原因狀語從句，常用的連接詞有：when while, as, since, before, after, once, as soon as, until, till 連接條件狀語的連詞有：if, unless, as long as 等，而原因狀語的連接詞有because, since, as, now that (既然)。目的、結(jié)果、方式、比較、地點等狀語從句的連接詞有：so that, so…that, such…that, as…as, than, where… 它們在句子與文章中幾乎無處不見。 具體用法見下表。
連詞用法一覽表
種類 功用 例句
并列連詞 連接具有并列關(guān)系的 詞 He knows neither English nor French.
短語 Are you going by bus or on foot?
分句 Mary was a good girl, but she had one shortcoming.
從屬連詞 引導(dǎo)： 狀語從句 I'll do it as you told me.
You will be late unless you hurry.
連接代詞和連接副詞 主語從句 What he said proved true.
When we'll start has not been decided yet.
表語從句 This is why he didn't come yesterday.
That is where he lives.
賓語從句 The man asked me which I liked best.
I can't understand why she is so late.
關(guān)系代詞和關(guān)系副詞 定語從句 Nicotine is a drug that gets one into the habit of smoking.
He came last night when I was out.
(二) 正誤辨析
[誤] Both my parents are not here. They went to the concert just now.
[正] Neither of my parents is here. They went to the concert just now.
[析] 在英語中both一般用于肯定句中，如用于否定句中，其意義也不同于漢語，如：Both of us are not right. 在英語中應(yīng)被理解為"我們倆不都對。"而Neither of us is right. 才能被理解為"我們倆無一正確".
[誤] He or his parents has some tickets for the film.
[正] He or his parents have some tickets for the film.
[析] 由or 連接兩主語時，謂語動詞應(yīng)與相臨近的那一個主語保持一致。
[誤] You should study hard, and you won't pass the exam.
[正] You should study hard, or you won't pass the exam.
[析] or作為連詞，這里的意思為"否則".又如：Hurry up, or you'll be late for school.
[誤] Though he is poor, but he is ready to help others.
[正] Though he is poor, he is ready to help others.
[正] He is poor, but he is ready to help others.
[析] "雖然……但是"是中文中的常用結(jié)構(gòu)，但在英文中用了"雖然"則不要用"但是",用了"但是"則不能再用"雖然",二者只可用其一。
[誤] Either you or I are on duty.
[正] Either you or I am on duty.
[析] either…or 連接兩個主語時，其謂語動詞與相臨近的一個主語相呼應(yīng)，這也叫作就近原則。類似的用法還有or, neither… nor, not only…but also等。
[誤] Tom is our English teacher and teaching English in our school now.
[正] Tom is our English teacher and is teaching English in our school now.
[析] 并列句中常常在后面的句子中作一些省略，以免重復(fù)，但不是所有詞都可作任意的省略的。當(dāng)你連接的是兩個系動詞時，后面的那個系動詞不可省略，也就是講連接的部分不可省略。
[誤] My father likes swimming and to collect stamps.
[正] My father likes swimming and collecting stamps.
[析] 由并列連詞連接的兩個部分要保持相等的語法結(jié)構(gòu)。如是動名詞則都用動名詞，如用不定式則都應(yīng)用不定式，這是初學(xué)者要注意的一點。
[誤] My father is reading a newspaper, I am doing my homework.
[正] My father is reading a newspaper while I am doing my homework.
[析] 兩個并列句中間不可用逗號連接，要用并列連詞來連接。
[誤] My father asked me that if I wanted to learn how to drive.
[正] My father asked me if I wanted to learn how to drive.
[析] 賓語從句的連接詞只能有一個不能重復(fù)使用。
[誤] We will go both to Beijing and Shanghai.
[正] We will go to both Beijing and Shanghai.
[析] 用both…and…作連接詞時，其相連接的部分結(jié)構(gòu)也要相同。
[誤] Not only Mary but also her brothers is going to dance.
[正] Not only Mary but also her brothers are going to dance.
[析] 由not only… but also…連接兩個主語時，其重點在其后面的那一個主語，所以謂語形式應(yīng)采用就近原則。
[誤] The teacher as well as his students are coming.
[正] The teacher as well as his students is coming.
[析] 由as well as 連接兩個主語時，謂語動詞與as well as 后面的名詞無關(guān)，而與前面的名詞相一致。
[誤] Tom does not swim nor play football.
[正] Tom does not swim or play football.
[析] nor主要用于連接句子的對等連詞，如在否定句中連接某一部分時要用or, 但要注意句子的含意，如：This animal does not like a cow or a horse. 這個動物既不像牛也不像馬。This animal does not like a cow but a horse. 這個動物不像牛而像馬。
[誤] For there is no light in the classroom. The students must have gone home.
[正] The students must have gone home, for there is no light in the classroom.
[析] 由for引出的原因狀語從句在使用時要注意不能將該從句置于句 首，而應(yīng)置于主句之后，并在主句與從句之間加一逗號。更要注意的是because, as, since與for 4個表示原因的連詞中because是因果關(guān)系，是最強(qiáng)的一個，而for是最弱的一個。有些語法書中干脆把for叫做并列連詞
[誤] My brother will pass the English exam is no question.
[正] That my brother will pass the English exam is no question.
[析] 主語從句的引導(dǎo)詞that是不可省略的。這一點不要和賓語從句的引導(dǎo)詞相提并論。
[誤] This map will show you how will you get to the hotel.
[正] This map will show you how you will get to the hotel.
[析] 名詞性從句作賓語從句使用時，最重要的一點是要用陳述語句。特別要注意的是那些使用雙賓語的動詞，如：tell, ask, show…
[誤] While the clock struch ten, all the lights went out.
[正] When the clock struck ten, all the lights went out.
[析] while是強(qiáng)調(diào)兩個動作在同時進(jìn)行中，如：While I am doing myhomework, my father is reading a newspaper. 而這里的when是"正當(dāng)某某時刻","就在這一時間點上",其重點強(qiáng)調(diào)在某一特定時刻某動作的發(fā)生。
[誤] While I was walking along the street yesterday, I met an old friend.
[正] When I was walking along the street yesterday, I met an old friend.
[析] 這里用when表達(dá)在一個動作的進(jìn)行中，另一個動作突然發(fā)生了。正在進(jìn)行的動作用一進(jìn)行時態(tài)，而突然發(fā)生的動作用一般時態(tài)。
[誤] While I heard the bad news I felt sad.
[正] When I heard the bad news, I felt sad.
[析] while不能表達(dá)一點兒的時間，即瞬時某一時間點。
[誤] After school some students play football, or others go to the library.
[正] After school some students play football, while others go to the library.
[析] while在此處意為"而，然而".
[誤] She sang when she walked along the dark street.
[正] She sang as she walked along the dark street.
[析] as用于句中時，其要點是強(qiáng)調(diào)兩個動作的同時進(jìn)行。這里用when雖然不能講是語法上的錯誤，但則看不出來小女孩因獨自走黑暗的街道因害怕而唱歌的心情。
[誤] I finished my homework until twelve o'clock last night.
[正] I didn't finished my homework until twelve o'clock last night.
[正] I did my homework until twelve o'clock last night.
[析] until用在句中時其含義是某一動作一直持續(xù)到某時結(jié)束，那么句中的動詞則一定要用持續(xù)性動詞，如果要用瞬間，或截止性動詞時一定要用否定句式。因截止 性動作的否定式應(yīng)看作是持續(xù)性的動作。如離開leave是瞬間動作，因一出門即為離開了，而不離開則是長時間的。
[誤] I have studied English when I was twelve.
[正] I have studied English since I was twelve.
[析] since引出的時間狀語從句是表達(dá)了一個時間點，而這個時間點是主句動作的啟始點，所以主句一般要用完成時態(tài)。
[誤] Because he didn't study hard, so he didn't pass the exam.
[正] He didn't pass the exam because he didn't study hard.
[析] because 與 so在英文中兩者不能并用的，只能在句中用其一。
[誤] He was such excited that he could not speak.