Помогите,плез,не понимаю10. Today the world _____ so rapidly; things never stay

Помогите,плез,не разумею
10. Today the world _____ so rapidly; things never stay the same.
1)changes
2)has changed
3)is changing
4)has been changing

11. When I first ____ to England in 1938, I thought I knew English fairly well.
1)came
2)had come
3)was coming
4)had been coming

12. Sara, my next door neighbour, has a car, but she _____ it very often.
1)doesn't use
2)isn't using
3)hasn't used
4)hasn't been using

13. It's raining, and I see you don't have an umbrella. You can borrow mine, I ______ it now.
1)don't need
2)did not need
3)haven't needed
4)haven't been needing

14. Suddenly they heard a strange noise and ______ at each other in horror.
1)looked
2)were looking
3)had looked
4)had been looking

15. What _____ this word mean?
1)Do
2)Does
3)Did