3) for用來補充說明一種理由，因此，for引導的從句幾乎可以放在括號里。For引導的句子不放在句子的開頭。例如：

　　I decided to stop and have lunch----for I was feeling quite hungry.

　�。�3）if, whether

　　if和whether都可作“是否”講，在引導賓與從句是一般可互換。例如：

　　I wonder whether (if) you still study in that school.

　　I don’t know whether (if) he likes that film.

　　在下列情況下，只能用whether,不能用if：

　　1) 引導主語從句時。例如：

　　Whether he will come to the party is unknown.

　　2) 引導表語從句時。例如：

　　The question is whether I can pass the exam.

　　3) 在不定式前。例如：

　　I haven’t made up my mind whether to go there or not.

　　（4）so…that, such...that

　　1) so…that中的so是個副詞，其后只能跟形容詞或副詞，而suchthat中的such是個形容詞，后接名詞或名詞短語。例如：

　　I’m so tired that I can’t walk any farther.

　　It was such a warm day that he went swimming.

　　2) 如果在名詞之前有many, much, little, few時，用so,不用such。例如：

　　He has so little education that he is unable to get a job.

　　I have had so many falls that I am black and blue all over.

　�。�5）either…or…, neither…nor, not only…but also…

　　這三個連詞詞組都可連接兩個并列成分。當它們連接兩個并列主語時，

　　謂語動詞要隨相鄰的主語變化。例如：

　　Either you or he is wrong.

　　Neither he nor his children like fish.

　　Not only the teacher but also the students want to buy the book.

　�。�6）although, but

　　這兩個連詞不能用在同一個句子中。例如：我們不能說“Although he is

　　over sixty, but he works as hard as others.”這個句子應改為：Although he is over sixty, he works as hard as others.或He is over sixty, but he works as hard as others.

　　（7）because, so

　　這兩個連詞同樣不能用在同一個句子中。例如：我們不能說“Because John

　　was ill, so I took him to the doctor.” 這個句子應改為Because John was ill, I took him to the doctor.或John was ill, so I took him to the doctor.

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