A:that; at
B:in which; over
C:which; about
D:where; to
植物的无性生殖所需要的主要条件是( )
A. Can I read the books here?
B. We usually talk quietly in the library
C. Keep your desk clean.
D. Take turns
已知|a﹣1|=4,|2﹣b|=5,求a﹣b的值.
若flnx=3x+4,则fx的表达式为( )