1. The students have improved.
2. She has become) really beautiful.
3. Man (invent) many great inventions.
4. Peoplehave caused) much destruction to the planet.
5. I (have learnt to surf.
6. The class has/have done) 5 tests this month.
7. Allison has found a few problems with your plan.
8. Wehave consulted) some doctors about this.
9. I (met) Debbie in the last week.
10. In the previous year, we (doubled) our income.
11. She has been sick since Sunday.
12. You have been away for 2 weeks.
13. Hehas hated cheese since childhood.
14. Mark and Katie have been together for two years.
15. I have liked mango since my last trip.