1. I (read)... the novel written by Jack London several times before
2. Vietnamese people (celebrate)... their Lunar New year around January or February
3. We should put some trash bín in the school yard (prevent)... students from littering
4. Our teacher always (come)... to class on time
5. If people stop using dynamite for fishing, a lot of creatures (be)... well preserved
6. I'm looking forward to (hear)... from you
7. The sad movie made me (cry)... a lot