Who that which

1. When we are talking about things, we use that or which (not who) in a relative clause.

1.1. That is my Math book.

1.2. That is an old house.

1.3. That is your wallet.

2. That is more usual than which. But sometimes you must use which (not that)

2.1. Which one of these cars is the fastest?

2.2. Which was the book you read last week?

2.3. Which was the lamp you broke?

3. We use relative clauses to give additional information about something without starting another sentence

4. We use who in a relative clause when we were talking about people. We use who instead of he/she/they

4.1. Who gave you this present? It’s beautiful

4.2. I don’t like the people who don’t say ‘thank you

4.3. I just wanted to know who was him