Your feet must be behind the line when you serve.
发球时你的`脚必须站在底线的外面。
She shifted her weight from one foot to the other.
她把身体的重量从一只脚换到另一只脚上。
It was the first time I had set foot on American soil.
那是我第一次踏足美洲大地。
You can back up another two feet or so.
你可以再退两英尺左右。
It was the first time I had set foot on African soil.
那是我第一次踏上非洲大地。