工人们正在粉刷货车的两侧壁板。

The workers are painting the ___sidewalls of the cargo truck.

轮胎的侧壁上有一个小鼓包，需要立即更换。

There's a small bulge in the ___sidewalls of the tire, it needs to be replaced immediately.

网球打得太用力，球撞到了场地的边墙。

The tennis ball hit the ___side wall after being struck too hard.