Before studying to frame questions, we have to learn all the most relevant question words and their purposes and also understand more about the types and patterns of interrogative sentences
If clause are in four types. They are ;
1. If clause in zero condition.
2. If clause in simple present tense.
3. If clause in simple past tense.
4. If clause in past perfect tense.
Whenever a subordinate clause begins with ‘If,’ then the subordinate clause, either denoting a condition or an imagination, can be called as an If clause.