1. The physics teacher was standing by the desk, explaining the exercise _____ the students had done at home.

A. /                 B. to                   C. for                   D. with

2. Harward, _____ in 1636, is one of the most famous universities in the U. S.

A. set                B. found               C. discovered        D. founded

3. Do you know what has _____ him?

A. become            B. become as         C. become of        D. become into