These four expressions (Suppose, Supposing, Imagine, What if) are interchangeable with “if” in conditional sentences. Simply substitute “if” with any of these expressions while maintaining the structure of the original “if” clause.
We use the present tense to describe real situations, as seen in the first conditional.
- Imagine you meet him in the street, what are you going to tell him? (First)
We use the past simple or past perfect tenses to describe hypothetical or counterfactual situations, like those seen in the second, third, and mixed conditionals.
- What if you found a suitcase full of money? What would you do? (Second)
- Supposing she hadn’t told you anything, you would have acted differently. (Third)
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