The ()for which he wanted to()with them is still unknown.

问题描述:

The ()for which he wanted to()with them is still unknown.
a.reason;cause c.reason;reason
answer:c and why?

第一个reason解作名词
第二个reason解作动词
翻译过来:
他想跟他们理论(第二个)的原因(第一个)还是未知