--When did this accident happen?

--It happened ________six o'clock ________ the afternoon of last Monday.

1. A.
   at; in
2. B.
   in; on
3. C.
   about ; at
4. D.
   at; on

--When did this accident happen?

-- It happened _______ six o'clock________ the afternoon of last Monday．

A．at; in              B．in; on              C．about; at            D．at; on