－Has Tom finished his job yet?

－I have no idea of it; he _____ it this morning.

A．has been doing　　　　　　　　　　　　　　 B．had been doing

　 C．did　　 D．was doing

一Has Tom finished his job yet?

－I have no idea of it；he       it this morning．

    A．did               B．was doing        C．has been doing   D．had been doing