3的相反数与-3的差是 [ ]
A.6
B.-6
C.0
D.-
答案：C
—Where Anna and Tony work?
— A factory. [ ]
A. is
B. does
C. do
D.are
1.2×104牛顿，按SI词头要求，写成（）。
A.12×103牛
B.0.12×105N
C.120×102牛
