The reason _____he was absent was _____ he was ill and unable to go to school.

A．which; that

B．why; because

C．which; because

D．why; that

“一国两制”的核心和实质是（）。

A.实现中国统一

B.和平解决台、港、澳问题

C.只有一个中国即中华人民共和国

D.以上都不正确