for free 免费 free of charge;for nothing
例句：
People living in that city can use their public transportation for free.
住在那个城市里的居民可以免费使用公共交通设施。
I got this for free.
我免费得到了这个。
A:Hey, would you like to go out for a movie with me tonight? I got two tickets for free.
嗨，今晚和我出去看电影好吗？我得到两张免费票。
B:I'd love to, but I have to finish my work first.
我很乐意，但是我得先完成工作。
