A:
B:
C:
D:
—________ will you ask for help when you get into trouble?
—My parents, I think.
将质量相等的实心铁块和铜块浸没在水中(ρ铁<ρ铜),它们的体积为V铁和V铜,受到的浮力为F铁和F铜,则( )