Defining relative clauses

Defining relative clauses give essential information about the noun that they follow. Without the relative clause the sentence would be incomplete and would not make sense.

This sentence is incomplete - it needs a defining relative clause.

• She's the teacher.......... She's the teacher who gave interesting lessons.
• Maths is the subject........... Maths is the subject that gives me most problems.
• I never understand any explanations........... I never understand any explanations which Mr Mitchell gives.