质量2.5kg的物体被200N的水平压力压在竖直墙上静止,如右图所示.此时物体对墙的压力是____N,此物体受到的摩擦力是____N.(g取10N/kg).
例句:My sister often asks me silly questions.
用适当的介词填空
(1)He was born____ a cold morning.
(2)The girl began to learn to play the piano____ an early age.
(3)The beautiful music was____ Gu Jianfen.
(4)We often watch concerts____ TV.
(5)The boy can play all types____ instruments(乐器).
小凡同学在做“观察水的沸腾”实验中