Give the correct tense of the verbs in brackets.5.2 had done to keep (do) a lot of research, he started writing his report. X 7. It's necessary for us (keep) our environment clean. solo. 8. By the time I came back last night, every one 9. English is not easy (go) to bed. v (learn) 10. When I arrived at the movie theater, the movie 6. After he (already/start
