（题文）Many books on science _____ since I went to college.
A. were bought B. have been bought
C. will be bought D. are bought
The sick girl _______ to the hospital at once.
A. must send B. be must sent C. must be sent D. be sent
The window of our house _______ once a week.
A. have been cleaned B. is cleaned C. are cleaned D. are cleaning
When ______ your school ________?
A. did, built B. was， built C. is， built D. was， building
My room _______ tomorrow.
A. is cleaned B. be cleaned C. will be cleaned D. is cleaning
______ trees usually _______ in April?
A. Have, planted B. Are, planted
C. have, been planted D. Do, planted
