物体由于______________而具有的能叫做重力势能，它的大小与__________和__________有关。
被举高；质量；高度
In Japan, people sometimes give special gifts. But they are not open. Later, people may the same gifts to someone else.
A．give up
B．give in
C．give away
D．give back
简述生态和谐的内涵。
