---How often do I need to feed the birds?---They______ food every day, or they w

题型：不详难度：来源：

---How often do I need to feed the birds?
---They______ food every day, or they will be hungry.

A．must give	B．mustn’t give
C．must be given	D．mustn’t be given

答案

C

解析

试题分析：句意: 我需要多久喂一次鸟？必须每天喂食他们，否则他们会饿的。主语they 是动作give的承受者，所以句子用被动语态be given，故排除A B 项。带情态动词的被动语态基本结构：情态动词+be +动词的过去分词，must be given必须喂，mustn’t be given一定不要喂。据题意选C。