题目内容：

When ____,the museum will be open to the public next year.
(A) completed (B) being completed
我想选B,因为我记得After后面就要being的,但是答案上面是 A,

优质解答

After是介词所以后面是名词,when后引导的是时间状语从句,being completed表示正在被完成,completed是省略,补全了是when it is completed,the……