That is the only way we can imagine _____ the overuse of water in students’ bathrooms.[ ]

This photo reminded the old man ___ the days when he was young.

She studies for an English test by_______the textbook.

–Don’t _____ this plan to the public until we give you the go-ahead.–OK. I will not.

After I expressed how sincerely I wished to get his help, he agreed to help me at last.— I can understand. ___________ .