1. 宾语不止一个时, 第一个that可以省略, 而其他的that常不可以省略。

e.g. I think (that) it will clear up this afternoon and that they will come to say good-bye to us.

解析: that 在引导宾语从句时常可省略,但在下列情况下常不可以省去:

4. People in that area often go hungry worries the local officials very much.　　　　 ( 误　　　　 )

　　　 That people in that area often go hungry worries the local officials very much.　 (　 正　　　 )

6. 作discuss等词的宾语时;

e.g. He was not sure whether he ought to laugh or cry.

　　　 I worry about whether I hurt her feelings

　　　 Whether he will come or not I don’t quite know.

　　　 We discussed whether we should close the shop.

　　　 She hasn’t decided whether to go or not. 1. I don’t know whether / if I can come. = I don’t know whether I can come or not. 2. We worried about whether he was in good health or not. 3. The question is whether you can do it yourself. 　 Whether they will win is all the same to me. 　 The question whether he should come himself or send another one hasn’t 　been decided. 4. I haven’t decided whether to go there or not.

误区四: 遗漏连词that

5. 放在不定式前,与不定式组成词组时;

4. 引导主语从句、表语从句以及同位语从句时；

3. 从句提前时;

2. 作介词时的宾语时;

1. 从句中提出两种选择时,或句中有or not时；

3. If the famous scientist will come to attend the agricultural conference is not known yet.(　　 误　　 )

　　 Whether the famous scientist will come to attend the agricultural conference is not known yet. 　正)

解析：if 与whether引导宾语从句时经常可以互换。但在下列情况下常使用whether:

2. Why farmland here is being lost is because farmers have cut down too many trees in recent years. (　 误　　 )

　　　　 Why farmland here is being lost is that farmers have cut down too many trees in recent years.　　 (　 正　　　 )

解析：why引导的名词性从句或 reason作主语时，引导表语从句的引导词用that而不用because。Because也可以引导表语从句，常用于This / That is because…的句式中。

误区三：混淆if与whether的用法

Whether可以用于所有的名词从句中，if常用于宾语从句中，两者都不能省略。