A:to speak, many
B:not to speak, many
C:to speak, much
D:not to speak, much
在冬天,剩有半瓶热水的暖水瓶经过一个夜晚后,第二天拔瓶口的软木塞时觉得很紧,且不易拔出,其主要原因是( )
对下列现象的形成,判断正确的是( )
在探究有关浮力的实验中: