It sounds like a good idea, but I don't think it will work practically.

　　這個(gè)主意聽(tīng)起來(lái)不錯(cuò)，但我認(rèn)為它實(shí)際上行不通。

　　It sounds like a good idea; let's look at the practicalities and work out the costs.

　　這個(gè)主意聽(tīng)起來(lái)不錯(cuò)。咱們來(lái)看看實(shí)際運(yùn)作，計(jì)算一下費(fèi)用。

　　I know it sounds crazy but it just might work.

　　我知道這事聽(tīng)起來(lái)很蠢，然而也許就會(huì)奏效。

　　I know it sounds corny, but it really was love at first sight!

　　我知道這聽(tīng)起來(lái)像陳詞濫調(diào)，然而的確是一見(jiàn)鐘情啊！

　　I know it sounds trivial, but I'm worried about it.

　　我知道這事聽(tīng)起來(lái)微不足道，但我還是放心不下。