Biểu thức \(\dfrac{1}{2-\sqrt{3}}=a+b\sqrt{3}\) . Gía trị \(a^2+b^2\) bằng?

Số nghiệm của pt: \(x^4+3x^2=0\)

Số giá trị nguyên của x để biểu thức \(\dfrac{2\sqrt{x}-7}{\sqrt{x}-1}\) có giá trị nguyên là?

Rút gọn biểu thức \(A=\dfrac{\sqrt{x^6y^2}}{xy}\)  với x<0, y>0

Tính tổng sau: \(S=\dfrac{1}{2+\sqrt{2}}+\dfrac{1}{3\sqrt{2}+2\sqrt{3}}+\dfrac{1}{4\sqrt{3}+3\sqrt{4}}+...+\dfrac{1}{100\sqrt{99}+99\sqrt{100}}\)

Tính gía trị của biểu thức \(T=\dfrac{1}{\sqrt{1}+\sqrt{2}}+\dfrac{1}{\sqrt{2}+\sqrt{3}}+...+\dfrac{1}{\sqrt{99}+\sqrt{100}}\) 

1. I was in the countryside some weeks ago I ..... very relax.

a. feel       b. fell      c. felt        d. am

2. Yesterday, he ..... home and ..... to the cinema.

a. leaves/ drove      b. left/ drove        c. was leaving/ drove       d. leaves/ drives

3. They ..... at the petrol station and ..... some petrol.

a. stopped/ get       b. were stopping/ getting      c. stopped/ getting     

d. stopped/ got

4. She ..... to the river and .... into it.

a. running/ jumps         b. ran/ jumped        c. ran/jumps         d. run/ jumps

5. My mother ...... me a new bike two months ago.

a. bought       b. buying       c. to buy        d. buys

1. When I .... him, he was living in London.

A. last saw                B. last see               C. see            D. was seeing

2. We haven't seen Dorothy since she, ...... an accident.

A. has had            B. had            C. has             D. was having

3. The train ...... half an hour ago.

A. has been leaving             B. left           C. has left           D. had left

4. Jack ..... the door before going out 2 hours ago.

A. has just painted         B. painted            C. will have painted         D. painting 5. Christopher Columbus ..... American more than 500 years ago.

A. discovered   B. has discovered   C. had discovered   D. has been discovering

6. He said he ......... return later.

A. will             B. would.              C. can              D. would be

7. Almost everyone had left for home by the time we .........

A. arrive          B. had arrived        C. arriving           D. arrived

8. While her husband was in the army, Mary ..... to him twice a week.

A. was writing     B. wrote        C. was written      D. had written

9. Since ......, I have heard nothing fom him.

A. he had left       B. he left       C. he has left         D. he was left

10. After I had had lunch, I ..... my bag.

A. looked at         B. looked for             C. had looked for        D. looking for

11. The man got out pf the car, ........ round to the back and opened the book

A. walking           B.walked        C. walks           D. walk

12. Her father ..... when she was a small girl.

A. dies            B. died        C. has died                D. had died

13. Last week, my professor promised that he ..... today.

A. would come    B. will come          C. comes         D. coming

14. Pasteur ..... in the 19th century.

A. was living          B. lived          C. had lived           D. has lived

15. We ..... to go on a picnic and ....... a hotel last month.

A. decided/ rented      B. decided/ rent       C. decide/ rented       D. decide/ rent

Hoàn thành các câu sau, sử dụng "Used to": 

1. I/ used/ help/ her/ her homework/ school.

2. We/ not/ used/ work/ together/ the farm/ when/ we/ the countryside

3. you/ used/ go home/ late/ night?

4. They/ used/ play soccer/ street/ 5 years ago?

5. He/ used/ practice/ speak/ English/ his brother

6. She/ used/ wash/ iron/ clothes/ when/ her mother/ out/ last year?

7. Mr Lam/ used/ plough/ field/ his buffalo/ 2005/ to/ 2009

8. your from teacher/ used/ ride/ bike/ school/ two/ years/ ago?

9. cat/ used/ lie/ under/ bed/ last year

10. those children/ used/ absent/ class/ when/ they/ secondary school?

Chuyển các câu sau sang câu bị động:

1. He interrupted me while I was talking yesterday

2. They built this bridge in 1997

3. He fed the chickens before home this early morning.

4. We didn't follow her to the markets last Sunday

5. Tony saw his new neighbor breaking into the bank last night

6. Did you collect coins many years ago?

7. Did she do a test last Sunday morning?

8. They didn't give the book back to her

9. She washed the clothes in this river 2 hours ago

10. I cooked chicken soup last night