Our classroom ____ every day.

Our classroom ____ every day.
△△△丶Our classroom ____ every day.A.must clean B.is clean C.must be clean
D.must be clean
▲▲▲丶这道不是选择题是根据句意写出句子中空缺处单词的正确形式、
1.Mr Wang enjoys ____ by air(travel)
2.If it ____ tomorrow .I will go out.(rain)
3.Mary______ English for six years (learn)
= = = = =
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