问题补充:
The flowersevery day, or they’ll die.
A. can be watered
B. should water
C. must be watered
D. water
答案:
A. can be watered
B. should water
(答案→)C. must be watered
D. water
解析:句意:这些花必须每天都浇水,不然会死去。句子要用被动语态,其结构为be+动词过去分词;如果前面有情态动词,be用原形;情态动词can能够;must必须;结合语境故选C。