How do you study _____ a test? -- I study _____ making flashcards
His close friend _____ for two years.
There was a rainstorm yesterday. The flood _____ the old bridge over the small river.
She finished the work _____ as soon as possible. She’s very happy now.
—Do you know him? —I’m sure I’ve seen him _____, but I can’t remember the right place.
What can we students do _____ the environment?