Change the verb into the correct form:
1. The students (improve).
2. She (become) really beautiful.
3. Man (invent) many great inventions.
4. People (cause) much destruction to the planet.
5. I (learn) to surf.
6. The class (do) 5 tests this month.
7. Allison (find) a few problems with your plan.
8. We (consult) some doctors about this.
9. I (meet) Debbie in the last week.
10. In the previous year, we (double) our income.
11. She (be) sick since Sunday.
12. You (be) away for 2 weeks.
13. He (hate) cheese since childhood.
14. Mark and Katie (be) together for two years.
15. I (like) mango since my last trip.