求助关于TELL 后宾语从句的用法

The teacher told us ( )we worked out the probiem was important. 我想问一下( )内应填how 还是what．我们老师说应该用how，不能用what.我不明白为什么，谁能清楚明白的讲解一下

tell（sb) 后面可以跟 that(if, whether, what, when , where, which, why, who, whom, whose, how, whatever, whichever, whenever, however, whoever等）引导的宾语从句。注意事项：

1. 当that 引导宾语从句时, that可以省略。例如：

He said （that） he was leaving for Japan. 他说他要去日本。  

 2.  引导宾语从句的that在下列情况下一般不省略： 

（1）.宾语从句前有插入语。例如： 

We hope, on the contrary, that he will stay at home with us. 恰恰相反，我

们希望他和我们呆在家里。 

（2）有间接宾语时。例如： 

He told me that he was leaving for Japan. 他告诉我他要去日本。 

（3）有两个或两个以上that引导的宾语从句时， 第一个that可省略，其余的不能省略。例如： 

He said (that) the book was very interesting and that(不省略) all the 

children like to read it.他说那本书很有趣，所有小孩都喜欢读。 

（4）在“it(形式宾语)+补语”之后时。例如： 

I think it necessary that he should stay here. 我们认为他有必要留在这里。 

（5）that从句单独回答问题时。例如： 

—What did he hear? 他听说了什么事？ 

—That Kate had passed the exam. (他听说)凯特考试及格了。