Costless
a. 沒有成本的, 不需花錢的
? 同義詞
??? 情景例句
Well, it's hard work.
嗯 這種工作很辛苦。
Which would you prefer, a smoking seat or a non-smoking seat?
你喜歡哪種，吸煙座還是禁煙座呢？
What is it?
什么問題。