41. I think you should complain _______, of course, you are happy with the way things are.
A. unless B. if C. although D. because
42. Getting a new computer system ____ at the school has become a high priority（首要事情）.
A. installed B. installing C. to be installed D. having installed
43. _______happened to be no one in the building when the fire broke out.
A. It B. There C. This D. That
44. — He should have come to join in the thorough cleaning.
—He _____, I think. It’s not his turn.
A. needn’t have to B. needn’t have C. didn’t have to D. doesn’t need to
