-- Do you know the boy _______ is sitting next to Peter?
-- Yes. He is Peter's friend. They are celebrating his ____ birthday.
A:who, ninth
B:that, nineth
C:/, nineth
D:which, ninth
如将一只盛有水的薄塑料袋,用细线扎紧袋口,用弹簧测力计测得其重力为9N,再将这个装水的塑料袋浸入水中,当弹簧测力计示数为7N时,袋内水面与袋外水面相比较()
如图是a、b两种物质的质量与体积的关系图象,分别用a、b两种物质制成两个规则的实心长方体甲和乙.下列说法中正确的是(ρ水=1.0×103kg/m3)( )
请回答下列问题:
下列说法正确的是( )