―Is Tom coming to the concert this evening?

―No, he _________ be at the concert. He _______ abroad.

A．mustn’t, has been

B．mustn’t, has been to

C．can’t, has gone to

D．can’t, has gone

在调用函数时，如果实参是简单变量，它与对应形参之间的数据传递方式是______。

A．地址传递

B．单向值传递

C．由实参传给形，再由形参传回实参

D．传递方式由用户指定