The reason ________ he left the room is obvious.

A、 historical reason and class reason

B、 historical reason and psychological reason

C、 class reason and psychological reason

D、 extra-linguistic factors and linguistic factors

A.to have reason

B.to be reason

C.reasonable

D.reasonably

It is (reason) ______ for parents to pay for their children's education.

The reason why + 句子 ~~~ is that + 句子 (...的原因是...)

A.resource

B.reason

C.root

D.source

That is the reason why ~~~ (那就是...的原因)

I thought her request for financial aid was ___(reason), but somehow it was refused.

A.reason

B.cause

C.effect

D.fact