You see, these shirts are very nice. I really don't know____________.

1. A.
   what to buy
2. B.
   how to buy
3. C.
   which to buy
4. D.
   when to buy

[　　]

You see, these coats are very nice. I really don't know ________.

[　　]

—Nice to see you．I         you for a long time．

        —I          in Beijing．I’ve just got back．

        A．hadn’t seen；was                  B．haven’t seen；shall be

        C．haven’t seen；was                 D．didn’t see；have been