大型中餐宴会，应提前（）左右上冷菜。．

A.5min

B.8min

C.15min

D.30min

下列函数中对调用它的函数没有起到任何作用的是( )。

A．void f1(double &{--x;}

B．double f2(double {return x-1.5;}

C．void f3(double {--x;}

D．double f4(double *{--*x; return*x;}