When English speakers use the phrase "open up" it means revealing feelings and experiences. For example, " She really "opened up" and told me what was bothering her. I think I finally understand the issues." The phrase "start up" is a way of describing the opening of business. For example, "The store had a successful "start up. Their first week of operation had over 1000 customers". The phrase "meet up" is used when you already know someone and you want to make arrangements. For example, "Can we "meet up" for coffee again next week?" All three of these examples are called "phrasal verbs". They are usually made up of a verb and a preposition. They are used often in English to give new and more precise meaning to situations. Hope this helps

Well, there isn't that big of a difference between them. Open vs. open up - pretty much the same but maybe open up is a little less formal. Open - Open the door Open up - Open up the door (maybe someone is angry and wants someone to open the door. Or maybe they are in a hurry.) start vs start up - well these can be two different terms start - lets start the meeting start up - He works at a start up (a self-owned small business) You can also say 'the car won't start up' or 'the car won't start'. Start up is just less formal. Meet vs meet up - again, meet up is less formal Meet - Let's go meet the new boss Meet up - let's go meet up with the new boss (maybe whoever you're talking to is a friend or somewhat close to you)