I'm thirsty. I want ______. [ ]
A. a hamburger
B. some water
C. a cake
D. some meat
答案:B
下列各式中,运算正确的是( )
A.3a+b=3ab
B.-(3x-2)=-3x-2
C.-2(x+4)=-2x-8
D.4xy2-6yx2=-2y2x
上海居民参加大病保险需要缴费吗?