Could, would, and should. Your teachers should have taught you about these words. We use "should" to talk about an obligation or requirement. If you want to cancel a class, you should tell the teacher in advance. If you were my student, I would have taught you these words. We use "would" to talk about choices, and it usually follows "if". If you cancelled my class without warning, I would expect to get paid for it. Maybe you could look in a book instead of asking here? We use "could" to talk about possibilities, what can be done, and it's often used in a sentence with "would". I could tell you to look in a book, but I'm going to tell you the answer. If I could answer every question for every student, I would be very happy. If you have a question, you could look in a book but I would be happy if you asked the question here. All the teachers here should be happy to help you.

It's helpful if you can say more about what your job will be. Business is a very wide topic. The series "Silicon Valley" is about a group of young men starting a technology business. The movie "The Big Short" is about the financial industry. They are very different situations. I am a teacher with 15 years experience and currently teach university in China. Based on your writing, I would say that your English is probably not at the right level to be watching movies and understanding enough to learn anything. It would be far more effective for you to get a decent book on Business English and do the exercises that are designed to help people like you. They are written by experts, they go at the right speed, they explain everything as they go along. Don't try to run before you can walk, for your own sake.

You'll probably get more answers, and better ones, if you ask one question at a time. There are four different topics here. Too much!

This is not a natural sentence, it's awkward and the grammar is poor. It's English with Chinese characteristics. You won't learn anything by studying this kind of stuff, and I'm not going to waste my time trying to make sense of it for you. The internet is full of authentic English, written by native speakers who know how the language works. Why are you using material written by Chinese people? If you are serious about improving your English, throw it away, and start using grammatically correct, natural-sounding material instead.

Lotus, please stop studying Chinglish. Don't read anything else in English that is written by Chinese people. Use authentic materials produced by native-speakers. This rubbish is not going to help you at all. The internet is full of texts in good English. Please use them.

This is the right way to do something. You already did it? You did the right way, or a great way. That's a great way to do it. Well done! Note, we often use it sarcastically, to mean that someone did something wrong. "You told my wife about the party? Way to go, Damon. Now she knows where I am going."

They are fine examples of words with clear specific meanings. There are situations where these words are essential. They are relatively modern ideas, so there isn't a lot of alternative vocabulary. If you want to talk about this specific topic, then these are the words you need. In all other situations, you don't have any use for them, or for alternatives. If you're not talking about structures of corporate entities and ownership, you can forget them.