Cho x và y là hai đại lượng tỉ lệ nghịch. Gọi x1, x2 là hai giá trị của x và
 y1, y2 là hai giá trị tương ứng của y . Biết rằng x1 - 5x2 = -39 và y1 = 8, y2 = -12 , hãy:
a) Tính x1, x2;

b) Biểu diễn y  theo x .

Exercise 1. Are the following sentences correct or not? If the sentence is correct,put a tick. If not, underline the mistake and correct it.

1. Not only he twisted his ankle but he also dropped his wallet.

2. Look, there go the children on their way to school.

3. Only recently have scientists discovered a cure for certain types of leukaemia.

4. "I'd rather have a walk in the morning." — "So I would."

5. Down in the valley did a fertile-looking vineyard lie.

6. Not until do you grow up, we will let you live independently.

7. Into the valley of death rode the six hundred.

8. Everybody didn't believe what she said, and neither didn't I.

9. Right through the underwater tunnel swam she.

10. Such the force of the earthquake it was that the whole village has been devastated.

Exercise 2. Complete each sentence by using the phrases from the box.

1. ____________ are passengers allowed to carry more than two pieces of hand luggage.

2.  ____________ had the alarm gone off when the police cars arrived.

3.  ____________I asked a passer-by did I realize where I was.

4. I thought,  ____________did my colleagues, that the recession would soon be over.

5.  ____________was the media interest in the wedding that there were over a dozen photographers.

6.  ____________during the party did anyone mention that Peter and Julie were getting married.

7.  ____________you to pay the full amount, there would be a ten percent discount.

8.  ____________had it stopped raining than the sun came out.

9.  ____________protecting its habitat can we hope to save the species.

10.  ____________did the passengers know that the driver was an undercover police officer.

Exercise 3. Rewrite the following sentences, beginning as shown.

1. The substance is so toxic that protective clothing must be worn at all times. => SO

2. A boy sat on the fence looking lost and alone.

=> On

3. No matter what happens, Jane will never forgive Mark for what he did.

=>Under

4. If everybody in this country contributed one euro, the charity would reach its target. =>Were

5. I saw Owen last week and I realized then how much weight he had lost. =>Only when

6. It is the first time a book has moved me so much. =>Never before

7. The demands of an astronauts body are so great that above - average physical fitness is required. =>Such

8. We'd never have trusted him with our money if we'd known the truth. =>Had

9. Monica won first prize and she was offered a promotion too. =>Not only

10. The twins started screaming the minute the aeroplane took off. =>No sooner

                                                                                           Yes                  No

1 something she wants to stop                                      

2 a new hobby she’d like to start

3 where the word ‘January’ comes from

4 common resolutions people make

5 why people make resolutions in December

6 how many resolutions aren’t successful

7 why some resolutions fail

8 why January is a bad time for resolutions

9 why she can’t take up running

10 a time when it’s easier to break habits