他单脚跳着穿过了房间。

He ___hopped across the room.

那个精力充沛的孩子在游乐场里单脚跳来跳去。

The energetic child was ___hopping around the playground.

因为一只脚疼，她不得不小心翼翼地单脚跳上楼梯。

With one foot sore, she had to ___hop up the stairs carefully.