Question

—It is so hot today. Why not swim in the river?

—No, we can't swim in the river. Our teachers and parents always warn us ________in the river. It's too dangerous.

A.to not swim B.swimming C.not to swim D.not swimming

Answer

C

【解析】

句意：——今天太热了。为什么不在河里游泳呢？——不，我们不能在河里游泳。我们的老师和父母总是警告我们不要在河里游泳。这太危险了。

考查动词不定式的否定形式。警告某人不要做某事warn sb. not to do sth或warn sb. against doing sth，结合选项，可知用warn us not to swim in the river “警告我们不要在河里游泳”，故选C。