These sentences contain the word 'if'. There are two types of conditionals : the real , which is habitual or factual and the unreal, which may never happen. The real condition is used when we express an action or a situation which will really happen or likely to happen.
In conditional sentences, there are two clauses. The 'if' clause and the subordinate clause which should contain the modal auxiliaries will, would, can and could. Please note: The modal auxiliaries should not be used in the 'if' clause and only be used in the subordinate clause.
For example: If I meet Raj, I will invite him for lunch.(Present tense)
If I met Raj, I would invite him for lunch (Past tense)
If I had met Raj, I would have invited him for lunch(Past perfect)
Unreal conditions(Not true)
In the unreal condition ,we should use only 'were' with all the persons(First person: I, We. Second Person: You Third person: he, she , it, they.)
You should never use: was.
For example: If I were a bird, I would fly in the sky.
If you were rich, You would buy me a house,.
If he were the Prime minister, he would build many free schools.
If I have the money, I will build a good school.
If she saw the accident, she would faint.
If she had seen the accident, she would have fainted.
If today were Sunday, we could watch a movie