plunge 和 dive 和 swim 的差別在哪裡？如果不好說明，請提供一些例句。

Plunge is associated with an immediate dive or jump into water.
Ex. "He plunged into the icy water." This means that he jumped or dove or got into the icy water. It can be used interchangeably with "dive" depending on the sentence and context.

Dive means to jump into water in a certain stance, usually with the arms above the head where the arms touch the water first. However, you can still dive into water going feet first too.
Ex. He dove into saltwater pool."

Swim means to actually be in something and use your arms and legs to get where you're going. Usually this term will be associated with someone swimming in water. Although, it can be used to say someone is swimming in something else.
Ex. "He will swim in the pool on Saturday."
Ex. "He was swimming in tears." (English language expression)
Ex. "He was swimming in sweat." (Gross.)
Ex. "He is swimming in cash." (He has lots of money!)