Who vs Which Exercises

In English, we use who for people and which for things when we want to add extra information about a noun. For example: "The teacher who helped me was very kind" — teacher is a person, so we use who. "The book which I bought is really interesting" — book is a thing, so we use which. You can also use that for both people and things: "The teacher that helped me" and "The book that I bought" are both correct and very common in everyday English.

A common mistake is using which for people — "The man which called me" is wrong. It should be "The man who called me" or "The man that called me." A simple test: if you are talking about a person, always choose who or that. For animals, you can use either which or who, but which is more common. For places, use where, and for times, use when — you will learn these in later exercises. This basic who vs which rule is a key building block for more advanced grammar.