I wonder when she was here

问题描述:

I wonder when she was here
when 还可以相等于which加什么?
2,The problem is ( )we should do ( )him.
a,what,to help b,that,and help c,how ,to help d,why,and help
(b,c,d不选的原因,麻烦详细些)

b,c,d不选是因为do是及物动词 后面应该接谓语 而只有a有 what做它的谓语
when应该等与at which time吧