5. Although, it's raining, ____are still working in the fields.

A. they　　　　　 　　　 B. but they　　　 　 C. and they　　　　　　 D. so they

4. Why these things happened was ____ the driver had been careless.

A. because of　　 　 B. owing to　　　　　　 C. due to　　　 　 D. that

3. They had camped once before, ____ they knew what to take.

A. because　　　 　 B. now　　　　　 　　　 C. so　　　　　 D. since

2. ____ you are dismissed.

A. Neither you go nor 　 B. Either you go or 　 C. Whether you go or　 D. Both you go and

1.He is very old,____ he still works very hard.　 　 A. but　　　 B.if　　　 C.when　　　　 D.as

10、as作從屬連詞可引導(dǎo)多種狀語(yǔ)從句。①as引導(dǎo)時(shí)間狀語(yǔ)從句，意為“當(dāng)…時(shí)”。例如：As (he was) a young man, he was a storekeeper and later a postmaster./ He sang as he worked.　 ②as引導(dǎo)方式狀語(yǔ)從句，意為“象…一樣”。例如：We must do as the Party teaches us.�、踑s引導(dǎo)原因狀語(yǔ)從句。意為“由于”，例如：As you are tired, you had better rest.�、躠s引導(dǎo)讓步狀語(yǔ)從句。意為“雖然”、“盡管”Child as he is, he can do it well. ( = Although he is a child, he can do it well.)　 另外，as做為關(guān)系代詞還可以引導(dǎo)定語(yǔ)從句，如：I have the same book as you.

練習(xí)、連詞

9、whether, if引導(dǎo)從句的用法區(qū)別：①引導(dǎo)主語(yǔ)從句、表語(yǔ)從句或同位語(yǔ)從句時(shí)，用whether，不用if。例如：Whether they will go to the Great Wall is not known./ The question is whether we can finish the task on time./ The question whether we will take part in the physics contest has not been decided. ②whether可接不定式，而if則不可。例如：I haven’t decided whether to leave or not. ③whether可作介詞的賓語(yǔ)或置于句首表示強(qiáng)調(diào)，而if則不可。例如：Everything depends on whether we have enough money./ Whether he will come, I am not sure. ④whether和if均可引導(dǎo)賓語(yǔ)從句， whether引導(dǎo)的賓語(yǔ)從句一般都是肯定句，if引導(dǎo)的賓語(yǔ)從句可以是肯定的，也可以是否定的(此時(shí)不能用whether)，例如：Could you tell us whether/ if it rains in winter in Australia?/ I wonder if it doesn’t rain. ⑤引導(dǎo)賓語(yǔ)從句的whether和if常可與or not連用。連用時(shí)要注意or not的位置，它一般與 whether、if分開使用，有時(shí)它可與whether合起來(lái)使用，但不能與if合起來(lái)使用。例如：I don’t know whether/ if they will come or not./ I don’t know whether or not they will come.　⑥if可用來(lái)引導(dǎo)條件狀語(yǔ)從句，譯“如果”，whether則不行。例如：If you work hard, you are sure to succeed.

8、在用as if引導(dǎo)的方式狀語(yǔ)從句及表語(yǔ)從句中，根據(jù)情況要使用虛擬語(yǔ)氣。例如：He talks as if he knew all about it. 但有時(shí)也可用直陳語(yǔ)氣。例如：It looks as if it is going to rain.

7、unless引導(dǎo)條件狀語(yǔ)從句等于if … not …。例如：He’ll accept the job unless the salary is too low. ( = He’ll accept the job if the salary is not too low.)

6、once作副詞譯“曾經(jīng)”，作為連詞譯“一旦”，引導(dǎo)條件狀語(yǔ)從句。相當(dāng)于if的加強(qiáng)形式。例如：I don’t believe he was once a thief. (once這里是副詞)/ Once Aristotle had made up his mind that heavy objects always fell faster than light objects, he taught it as a truth to his students. (once連詞)