______, flowers need a lot of sun and water.

______, flowers need a lot of sun and water.
A、When growing
B、They are growing
C、When they growing
D、When growth
【正确答案】：A
【题目解析】：A when growing 省略they are 主谓同时省略；B They are growing 已经是一句句子了，后面逗号+句子，是错误的，缺少个连接词；C When they growing 谓语无法单独省略；D When growth 被动语态在这使用明显不对；因此A正确