Remember to turn off the light when you leave.You believe what he did .You're really foolish. 这个你会不会转换don't believe what he did.you are really foolish.这是单个的两个句子。you are really foolish that you believe what he said.这就是一个带宾语从句的复合句you are really foolish to believe what he said .这也是一个简单句。