—Mom, my classmates invited me ____ a field trip. May I go with them?

—OK.

A．go on            B．to go on           C．go in             D．to go in

-- May I go out now. Dad?

     -- No. You __    let your mother know first.

  A. can                 B. may                 C. need               D. must

— May I go to the concert with you?

   — I’m afraid not ______ you have a ticket, because I have only one.

A. unless                    B. since                    C. if                     D. though

–May I go to the concert with you?
– I’m afraid not ______you have a ticket, because I have only one.

----May I go swimming this afternoon?

?? ----I'm afraid not _______ you have finished your homework.

A. unless????????????? ????????????? ????????????? B. because????????????? ????????????? C. if ????????????? ????????????? ????????????? D. though