聽起來 和 乍聽之下 和 乍一聽 的差別在哪裡？如果不好說明，請提供一些例句。

聽起來 means 'sound' : the idea sounds great. 這點子聽起來很不錯。
乍聽之下 and 乍一聽 means you perceive something when hearing, without time to think thoroughly, and most of the time the two are opposite.
他說的話乍聽之下有道理，但其實他根本在說謊。
What he just said sounds reasonable, but then I realized he was simply lying.
你的計劃乍一聽可行, 但執行起來問題重重
Your plan sounds feasible, but it turns out to be problematic when executing.