The students had much fun soccer after school.
A:playing
B:to play
C:played
外力对物体做功100J,物体向外放热20J,在这个过程中气体的内能____(填增大或减小或不变)内能的改变量是____J.
胞内蛋白质和分泌蛋白的合成部位( )