--How about ________ with us?

--All right.

1. A.
   have dinner
2. B.
   to have dinner
3. C.
   having dinner
4. D.
   has dinner

How about ________ with us to the museum?

1. A.
   come
2. B.
   comes
3. C.
   came
4. D.
   coming

—How about joining us in the summer camp?

—I wish I could, ___________ I have to practice for the piano test.

A．because          B．so               C．but              D．although