——I want to put up the picture on the wall. Would you mind helping me with it?—— ______. With pleasure.
A:Of course
B:Of course not
C:You'd better not
D:Thanks a lot
已知金属甲和金属乙的密度分别是ρ1、ρ2,取质量相等的金属甲和乙制成合金,这种合金的密度是( )
下列说法不正确的是( )