As If and As Though: Real Comparison, Evidence, and Unreal Distance

As if and as though compare an appearance or behaviour with a possible explanation. The tense choice tells the listener how close the speaker believes that explanation is to reality.

It looks as if it’s going to rain treats rain as a genuine possibility. He talks as if he knew everything uses a past form to create distance: the speaker does not believe he actually knows everything.

Past form does not always mean past time

This is the same grammatical distance found in wish, if only and would rather. With an earlier unreal event, use past perfect: She looked at me as though she had seen a ghost.

If the explanation seems plausible, present forms are normal: You sound as though you’re tired. For a wider view of unreal time, connect this pattern with mixed conditionals and counterfactuals.