1. Jane began learning Russian in 2012. (since)

 Jane has LEARNT RUSSIAN SINCE 2012.

2. We started studying for the exam last month. (since)

  We have STUDIED FOR THE EXAM SINCE LAST MONTH.

10. D

11. C

a) \(\left(x^2-25\right):\dfrac{2x+10}{3x-7}=\left(x-5\right)\left(x+5\right).\dfrac{3x-7}{2\left(x+5\right)}=\dfrac{\left(x-5\right)\left(3x-7\right)}{2}\)

b) \(\dfrac{x^2-4}{x^2-x}:\dfrac{x^2+2x}{x-1}=\dfrac{\left(x-2\right)\left(x+2\right)}{x\left(x-2\right)}.\dfrac{x-1}{x\left(x+2\right)}=\dfrac{x-1}{x^2}\)

1A

5A

7D

Exercise 4: Put the verbs in brackets: past simple or present perfect.

1. I (receive) RECEIVED  a letter just a few minutes ago.

2. They (live) HAVE LIVED in London since 1980.

3. Linda is working in this department. She (work) HAS WORKED here for two years.

4. Up to present, John (do) HAS DONE good work in the class.

5. (they/ put) DID THEY PUT their book on my desk last night?

6. He (study) HAS STUDIED English at this school for six weeks up to now.

7. Nobody lives in those houses. They (be) HAVE BEEN empty for many years.

8. Cindy is in her office. She (be) HAS BEEN  there since 7 o’clock.

9. My sister (come) CAME to see me last night.

10. My friend George is learning Japanese. He (learn) HAS LEARNED it for six months

a) \(x:0,25+x.0,25=3,4\)

\(\Leftrightarrow x:\dfrac{1}{4}+\dfrac{1}{4}x=3,4\)

\(\Leftrightarrow4x+\dfrac{1}{4}x=3,4\Leftrightarrow\dfrac{17}{4}x=3,4\Leftrightarrow x=3,4:\dfrac{17}{4}\)

\(\Leftrightarrow x=0,8\)

b) \(0,7:x+0,5:x=0,75\)

<=> \(\left(0,7+0.5\right):x=0,75\)

<=> \(1,2:x=0,75\)

<=> \(x=1,6\)

Chọn B nhé

21. Yes, there are.

22. In both museums.

23. They can see full of old weapons.

24. They can hire a small bus or taxi.

25. Yes, there is. They can see live snakes.

12,5 x 0,42 x 0,8 : 0,7

= (12,5 x 0,8) x (0,42 : 0,7)

= 10 x 0,6 

= 6

a, Tính từ : Thuở bé, tôi thường được nghe những truyện cổ tích rất hay và lý thú.

b, Động từ : Bé Na hay nấu cơm giúp mẹ.

c, Quan hệ từ : Cậu hay làm gì vào khi rảnh rỗi?