有些资料指出：“引导宾语从句的 that 通常可以省略。”

但是，有没有不能省略或者通常不省略 that 的情况呢？答案是肯定的。

1.若两个或者两个以上由 that 引导的宾语从句在句中是并列宾语，则第一个 that 可以省略，其余的 that 往往不省略。第一个由 that 引导的宾语从句较长时，尤其如此。例如：

Joe said (that) Peter would take them by car, but that they might be late. 乔说彼得将用汽车送他们，但也说他们可能迟到。（摘自《薄冰英语惯用法词典》p.1134）

He said he would come, and that he would bring his son. 他说他会来，而且会把他的儿子带来。（同上）

2.在agree, announce, argue, assume, aver, calculate, conceive, contend, hold, indicate, learn, maintain, object, observe, reckon, remark, reply, state, suggest 等动词之后，引导宾语从句的 that 一般不省略。

3. that 引导的宾语从句单独作为简短的答语时，that 不能省略。例如：

What did he say ? - That he would not commit himself too much. (= He said that he would not commit himself too much.)

4.如果that 引导的宾语从句与主句谓语动词之间有插入语，或者that 与宾语从句的主语之间有插入语，that 不能省略。例如：

Everyone could see, I believe, that George was terrified. （摘自章振邦主编：《新编高级英语语法》p.490）

He said that , if he could manage it , he would come. （同上）

5.如果为了强调而把that 引导的宾语从句置于句首，that 不能省略。例如：

That George was really afraid, I can’t believe.（摘自章振邦主编：《新编高级英语语法》p.490）

6. 在think, suppose, presume, dare say 后面由 that 引导的宾语从句中，that 通常省略。