so sánh K= 1/11+1/11^2+1/11^3+...+1/11^100 với 1

B= -x²+4x+1

|x - 3/2| = \(\sqrt[]{0,25}\)

13. You parcel _________________ (arrive). The postman _________________ (bring) it two hours ago.

14. He _________________ (be) at his computer for two hours.

15. We _________________ (live) there for ten years but we _________________ (be) in Birmingham for the last two.

16. We _________________ (not have) a party for ages.

17. My sister’s car is only a year old but she ___________________________ (already crash) it.

18. Dinosaurs _________________ (roam) the earth millions of years ago. 19. It _____________________ (not rain) yet today.

20. __________________________ (you see) last week’s magazine? - It must be here somewhere.