苯塔、甲苯塔收率一般要求达到()。
A.95%
B.99%
C.100%
参考答案:C
I can _____ be a teacher. I'm not a very patient person. [ ]
A. seldom
B. ever
C. never
D. always
单项选择。
Is your sweater old _______ new? [ ]
A.and
B.for
C.with
D.or