One reason that we haven’t had his letter is that he ________ it to our old address by mistake．

1. A.
   might send
2. B.
   may have sent
3. C.
   should send
4. D.
   should have sent

One reason that we haven’t had his letter is that he               it to our old address by mistake.

A. might send                                 B. should have sent

C. should send                               D. may have sent

One reason that we haven’t had his letter is that he ___it to our old address by mistake．

A．might send                                         B．may have sent

C．should send                                         D．should have sent

 One reason that we haven’t had his letter is that he  it to our old address by mistake.

A. might send       B. should have sent

C. should send      D. may have sent

One reason that we haven’t had his letter is that he ______ it to our old address by mistake.

A. might send　　　　　　   B.may have sent　　　　    C.should send　　　　　　   D.should have sent