It sounds like a good idea, but I don't think it will work practically.
這個主意聽起來不錯，但我認為它實際上行不通。
It sounds like a good idea; let's look at the practicalities and work out the costs.
這個主意聽起來不錯。咱們來看看實際運作，計算一下費用。
I know it sounds crazy but it just might work.
我知道這事聽起來很蠢，然而也許就會奏效。
I know it sounds corny, but it really was love at first sight!
我知道這聽起來像陳詞濫調，然而的確是一見鐘情啊！
I know it sounds trivial, but I'm worried about it.
我知道這事聽起來微不足道，但我還是放心不下。