we can’t understand is he didn’t join us in our discussion. A. That; whyB. Which; howC. Wh

问题补充：

we can’t understand is he didn’t join us in our discussion.

A. That; why

B. Which; how

C. What; what

D. What; why

答案：

A. That; why

B. Which; how

C. What; what

(答案→)D. What; why

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