21.step by step一步一步地；逐步地
Lorelei toiled step by step upwards.洛尔莱辛苦工作, 一步一步向上爬。
I am not rushing things and I'm taking it step by step.我不会仓促行事, 我会一步一步地来。
22.to watch your step<非正式>(behave well and carefully)谨慎行事(或说话)；谨言慎行
He's dangerous, watch your step!他是个危险人物, 你要谨慎行事！
Personally, I'd watch my step if I were you.就个人而言, 如果我是你, 我就会小心点。
(move carefully)留心脚下
Watch your step on that ladder!爬梯子时要注意脚下！