9. Four countries _were visited_ (visit) by John so far.
10. London _has____ (have) a population of eight million people.
11. Vietnam’s Independence Day _is celebrated__ (celebrate) on September 02nd .
12. We have visited_ (visit) Sydney Opera House for several times.
13. Some activities _are prepared_ (prepare) to celebrate the lunar new year now.
14. When I came to the stadium, the match (start) had started
15. Before she (listen) _listened_ to music, she (do)_had done homework.
16. Last night, Peter (go) _had gone__ to the supermarket before he (go) __went___ home.
17. Most students (leave) _had left____ before the volcano (erupt) ___erupted
18. I (find) __found______ my pen after I (buy)__had bought___ a new one.
19. Food and medical supplies (deliver)…were delivered….yesterday afternoon.
20. In the future, natural diasters (predict)…will be predicted… accurately with the help of technology.
21.Three cats (rescue) were rescued….by the volunteers last Sunday.
22. Two houses (build) …are built….in the city every year.
23. The Earth (hold) is held. by the gravity of the sun and orbits around it