一．单项选择
( )1.Don’t be_________. The students are having a lesson.
A. noise B. noisy C. noisily D. silent
( )2.I try my best to ________ his questions.
A. answer to B. reply C. reply to D. answering
( )3.I _______in that river, but the river is very dirty now.
A. use to swim B. used to swim C. used to going D. am used to go
