1.1. We use relative clauses to give additional information about something without starting another sentence. By combining sentences with a relative clause, your text becomes more fluent and you can avoid repeating certain words.
2. WHO: we use "who" in a relative clause when we are talking about people (not things). We use who instead of he/she/they.
2.1. 1- I work whit people who are responsible.
2.2. 2- She is engaged with a man who is very handsome.
2.3. 3- Mark is dating a woman who works in my company.
3. THAT: we use "that" in a relative clause when we mean a people or things.
3.1. 1- My brother bought a smartphone that is expensive.
3.2. 2- My son doesn't play video games that contain violent scenes.
3.3. 3- I don't like cell phone games that are not challenging.
4. WHICH: when we are talking about things, we use "which" in a relative clause.
4.1. 1- Every night I read articles which teach me something new.
4.2. 2- At work I use an old computer which is very slow.
4.3. 3- I work in a big company which has many employees.
