( ) 21. As we all know, the sun goes down in the _____________ .
A. east B. west C. south D. north
( ) 22. The Greens will have a ______ holiday in China. They love China a lot .
A. two week B. two weeks C. two-week D. two-weeks
( ) 23. I don’t think _____ is necessary for students to use a cellphone （手机）in school.
A. that B. this C. it D. one
( ) 24.—How high the mountain is !
—Yes. It's about 1000 meters _______ the sea .
A. on B. beside C. under D. above
