The flowers his friend gave him will die unlessevery day.A. wateredB. wateringC. waterD. t

问题补充：

The flowers his friend gave him will die unlessevery day.

A. watered

B. watering

C. water

D. to water

答案：

(答案→)A. watered

B. watering

C. water

D. to water

解析：unless后接省略形式。flowers和water之间是关系要用被动语态。同时unless从句的主语与主句的主语相同，常常省略其相同成分，故选A项，表示被动。动词-ing形式表示主动；不定式常用作目的状语。