1. If he (study) ___ harder, he can pass an exam. 2. She may be late if she (not hurry) ______. 3.If you study harder, you (pass) ________________ the exam. 4.If people really cared about the environment, they ( not dump )_________ waste into the lake. 5.If there was no fresh water in the world, what (happen) ________________. 6.If you (be)___________ the president, what would you do to help the environment ? 7.They get sick so often.If they exercised more, they (be) ____________ healthier. 8.If I (have) __________ one million US dollars, I would build more parks in our city. 9. Four countries ______________ (visit) by John so far. 10. London ______________ (have) a population of eight million people. 11. Vietnam’s Independence Day ________________ (celebrate) on September 09th. 12. We ______________ (visit) Sydney Opera House for several times. 13. Some activities ______________ (prepare) to celebrate the lunar new year now. 14. When I came to the stadium, the match (start) _____________________ 15. Before she (listen) _____________ to music, she (do)_____________ homework. 16. Last night, Peter (go)______ to the supermarket before he (go) __________ home. 17. Most students (leave) _____________ before the volcano (erupt) __________. 18. I (find) ____________ my pen after I (buy)_____________________ a new one. 19. Food and medical supplies (deliver)___________.yesterday afternoon. 20. In the future, natural disasters (predict)… accurately with the help of technology. 21.Three cats (rescue) _____________.by the volunteers last Sunday. 22. Two houses (build) ___________in the city every years. 23. Earth (hold)_____________ by the gravity of the sun and orbits around it. giúp mik vs ặ