playing的用法
playing是play的ing形式,be playing表示正在玩；my playing一般用于一些介词后,如I am proud of my playing.表示我为我的比赛游玩（一件事的过程）感到骄傲。
A group of kids were playing with a ball in the street.
一群孩子在街上玩球。
The children were playing in the sand.
孩子们正在玩沙子。
Germany is playing a leading role on the international stage.
德国在国际政治舞台上起着主导作用。