单选题：________ I can see, there is only one possible way to keep a..

He was about to tell me the secret _____ someone patted him on the shoulder. [ ]A. asB. until C. while D. when

— Do you know anything about that man?—No. I know nothing about him _______ I read in the newspaper yesterday.[ ]A. besides B. except whatC. except forD. except when

._______ there is going to be a policy change ________ of those things is going to change. [ ]A. Unless; fewB. Until; fewC. Unless; noneD. Until; none

We didn't have enough chairs, _____ some of the students had to sit on the floor. [ ]A. or B. as C. so D. but

短文改错 Recently, my classmates have had a heated discussion about if we should have optional courses(选修课) in high schools. Some students werein favor of optional courses. They say interest is bestteacher andour spare time will be colorful and meaningful. St