Must I practice the violin right now –No, you _____. You ______ do it later on.

See the flags on top of the building? That was _______ we did this morning.

She has been teaching in a school since she graduated,so she is not ________ to associating with business people. [ ]

It is written clearly in the requirements that all passengers _______ check onto board thirty minutes before the plane takes off．

n, my flight is being announced I must beoff now –Bye______________