Relative pronouns are words like that and which, and they are used to replace a word or phrase in a previous phrase or sentence. Using relative pronouns correctly increases clarity, and makes a text more formal. It is important to note that that the use of these words in writing may differ slightly from their use in spoken English.
ESL Tips on the Use of Relative Pronouns
Although there is no one single rule to cover all the cases, the following summary may be helpful if you need to make a quick decision:
- Use that if the main clause poses the question WHAT? answered by the relative clause;
- Do not use that presenting non-essential, additional information (that is, in non-defining relative clauses); use who or which instead;
- Use who to refer to people;
- Use which to refer to things or to refer to the previous clause as a whole;
- If you choose between who or that, use who in writing;
- If you choose between which and that, use which in writing;
- Do not put a comma before that.