1. When the students (hear)......heard....... the bell, they got up and left.
2. Minh (live)............has lived...... in Rach Gia city since 2010.
3. A: I don't know how to use this camera.
B: It's quiet easy. I (show)...'ll show..............you.
4. A: Why are you turn on the television?
B: I (watch)..am watching.............. the love story film.