1. The document introduces conditional clauses introduced by "if". It discusses the meaning of "if", the types of clauses it can introduce (conditional clauses), and the tense requirements in the if-clause. 2. It provides examples of if-clauses and examines the tense used in the if-clause and main clause. If the main clause is in the present or future, the if-clause is usually in the present. 3. It distinguishes if-clauses from object clauses, noting that if-clauses express conditions while object clauses complete the meaning of the verb.