It was unusual that such close neighbors ______ not know one another.
He made _____ experiments to prove his theory, and the number _____ added up to 600.
Had it not been for your help, I _____ penniless today.
No one can _____ how to deal with the matter.
No one likes _____ in public.
He was badly hurt last night. That is _____ he didn’t come to school.