4a2-12ab+9b2-c2.
原式=(4a2-12ab+9b2)-c2
=(2a-3b)2-c2
=(2a-3b+c)(2a-3b-c).
I like thrillers ______ I don't like actionmovies. [ ]
A. and
B. but
C. or
D. for
常用于细菌性脑膜炎的抗生素有()
A.头孢他啶
B.头孢曲松
C.头孢噻肟
D.万古霉素
E.利复星