What is the difference between a proposition and an offer? Thanks :)

I know what "listen up" means but I am not sure what "up" means and why it has to be "up"? I asked it to ChatGPT. Following is what it tells me about it. Breaking Down the Phrase: Listen: This simply means to pay attention to sound, especially with the intention of hearing something specific. Up: In this context, "up" is used as an intensifier. It doesn't have a literal spatial meaning here. Instead, it serves to make the command stronger and more urgent. But It think it has some specific meaning. Can anyone tell me about it more clearly?

What is difference between fast and rapid? Thanks :)

Here is a new question about phrasal verbs for you to try! Bonus question: is this phrasal verb separable or inseparable?

"When you become a member, it will unlock so many perks including more videos like this." In this sentence, should I say "you will unlock" instead of "it will unlock"? ChatGPT said "you will" is more natural and was wondering if that's correct.

Would you mind answering my question: "If someone isn't determined and often changes their ideas or opinion, they will be called a changeable person or a uncertain person." Many thanks for your help.

Are there any English native speakers who want to learn Russian? We can learn from each other.