Have you noticed the problem he is now in low spirit ? come?A. where What B. that HowC

问题补充：

Have you noticed the problem he is now in low spirit ? come?

A. where, What

B. that, How

C. in which, For

D. what, As

答案：

A. where, What

(答案→)B. that, How

C. in which, For

D. what, As

解析：that引导同位语从句，是problem的内容。后面的how come 意思是“怎么会那样？”符合上下文的意思。