—Is the letter from your mother?—Yes. But she ________ the letter herself, becau

题型：不详难度：来源：

—Is the letter from your mother?
—Yes. But she ________ the letter herself, because she doesn"t even know one word.

A．needn"t have written	B．can"t have written
C．might not have written	D．should not have written

答案

B

解析

选B　考查情态动词。句意：“这封信是你母亲来的吧？”“是的。但这封信不可能是她自己写的，因为她一个字也不认识。”根据because引导的原因状语从句可知，此处应用can"t have done表示对过去发生的事很有把握的否定推测。