choose
What if he .......come tomorrow?
it would be a disaster
(had not . did not. does not . will not)

find mistakes
the company that employees went on a strike was closed down.

did not
that > whose

did not
whose

ممكن حد من الأخوة الأفاضل يرفع امتحان المستوي الرفيع لو سمحتم

does not
whose

what will happen if he doesn't come tomorrow

didn't
whose]

didn't
whose