Question

【题目】—How often do I need to feed the birds?

—They food everyday,or they will be hungry.

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

Answer 1

【答案】C

【解析】句意：-我需要多久喂一次这些鸟？-他们必须每天被给食物，否则他们会饿的。must give必须给；mustn't千万不要给；must be given必须被给。根据句意可知，句中的主语They代指的是the birds，它和动词give构成被动关系，因此这里应填被动语态，故选C。