01、从句如果是陈述句，一般选择连词that，这里that 没有实际的意义，只是连接两个句子。所以，也可以把它省略掉。比如We all expect that they will win.

02、如果要表示是否的疑问语气的宾语从句，就要选择if或者whether.比如Nobody knew whether he could pass the exzam.

03、如果从句本身缺少主语，或者宾语，或者定语，或者表语等，就要选择疑问代词如who whom whose what whoever whomever whosever whatever 等。比如I don't know whom you should depend on.

04、根据意思和疑问语气，还可以选择疑问副词when where how why whenver.wherever however.比如He didn't tell me when we should meet again.

05、值得注意的是，what whatever 一般是指疑问，但也可以指陈述。比如The book will show yon what the best CEOs know.