With two sons ______ in Afghanistan, John and Susie Mayes are working extra hard this year to make sure their grandchildren have a great Christmas.

A．to serve

B．serving

C．having served

D．served

下列关于函数模板的定义中,合法的是( )。

A．template class ＜T＞T abs(T z) {return z＜0 -z:z;}

B．template＜typename T＞T abs(T z) {return z＜0 -z:z;}

C．template T＜class T＞abs(T z) {return z＜0 -z:z;}

D．template T abs(Tz) {return z＜0 z:z;}