He transplanted the rare flowers to the botany gardenit was the best time for them.A. wher

问题补充：

He transplanted the rare flowers to the botany gardenit was the best time for them.

A. where

B. when

C. until

D. that

答案：

A. where

(答案→)B. when

C. until

D. that

解析：考查状语从句。when引导时间状语从句。