English - Native speakers
posted by Mark .
Can we then say He may have come yesterday or just He might have come yesterday? Can we use may in the past tense or not?
They are pretty much interchangeable, yes.
Ok and the last one. Is there a singular form of sheets? Do we say change your sheets? (sheets on the bed, not a sheet of paper)
Yes, that word has both singular and plural form. You can refer to the top sheet, the bottom sheet, a fitted sheet (the ones whose corners are sewn so that it fits the mattress without having to be tucked in), a flat sheet, a crib sheet (for babies), etc.