【题目】—Catherine. I have cleaned the room for you.
—Thanks. You________it. I could manage it myself.
A．needn't do
B．needn't have done
C．mustn't do
D．shouldn't have done
在线课程【答案】B
【解析】“needn't have＋v.－ed形式”表示“(过去)没有必要”，“I could manage it myself”表明没有必要帮助把房间打扫干净。