问题
选择题
—Computer is so useful. It can do almost everything.
—Yes, but it ______ what to do.
A．will tell
B．has known
C．must be told
D．is told
答案
答案：C
题目分析：根据语境可知此句的含义是电脑很有用,它几乎能做任何事情,但它必须被告诉做什么.因主语是it,是动词的承受者,故用被动语态,根据语气可知要用含有情态动词的故用C.
点评：含有情态动词的被动语态，其结构为“情态动词can/could/may/might/should/will
/shall/would/need等+助动词be+及物动词的过去分词”
