--- Would you like to _____ Professor Smith’s lecture this Sunday?

--- Sorry, I have an important meeting to _______.

A．attend; join

B．join; attend

C．attend; attend

D．join; take part in

派生类构造函数的执行顺序是先执行【 】的构造函数，然后执行成员对象的构造 函数，最后执行【 】的构造函数。