17. the staff at the post office...happy with their working condition A.isn't B.wasn't C.weren't D.not been 18. gymnastics...an easy lesson at school A.is B.are C.were D.being 19. no 2 teams wear the same. each team...a different color A.wear B.wears C.have worn D.are wearing 20. there...some interesting pictures in today's paper A.is B.was C.has been D.are

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