I will not wait for him for a second – he may have something else to do, so he could not _____ here.

A．come up

B． come out

C．turn out

D．turn up

当事人互负债务，有先后履行顺序，先履行一方未履行的，后履行一方有权拒绝其履行要求，这是( )。

A．不安抗辩权

B．后履行抗辩权

C．先履行抗辩权

D．同时履行抗辩权