发球时你的脚必须站在底线的`外面。
Your feet must be behind the line when you serve.
她的脚从毯子一端露出来。
Her feet peeked out from the end of the blanket.
她脚未站稳，向后一仰掉进水中。
She lost her footing and fell backwards into the water.
我一个急转身，踩到了他的脚上。
I turned around quickly and stepped on his toes.
我的脚腕子还是疼得不能走路。
My ankle is still too painful to walk on.