Đặt A=n(n+13)

Nếu n=2k(kEN) thì A=2k(2k+13)=4k²+26k

Vì 4 chia hết cho 2 nên 4k^2 chia hết cho 2

Vì 26 chia hết cho 2 nên 26k chia hết cho 2

=> 4k^2+26k chia hết cho 2 hay A chia hết cho 2

Do đó, với n=2k thì A chia hết cho 2

Nếu n=2k+1(kEN) thì A=(2k+1)(2k+1+13)=(2k+1)(2k+14)=2k(2k+14)+(2k+14)=4k²+28k+2k+14=4k²+30k+14

Vì 4 chia hết cho 2 nên 4k^2 chia hết cho 2

Vì 30 chia hết cho 2 nên 30k chia hết cho 2

có 14 chia hết cho 2

=> 4k^2+30k+14 chia hết cho 2 hay A chia hết cho 2

Do đó, với n=2k+1(kEN) thì A cũng chia hết cho 2

Vậy n(n+13) chia hết cho 2 với mọi số tự nhiên n

câu nào 

III. Put the correct verb forms of the verb in brackets.
1. "Do you mind if I sit here?" - "I'd rather you (sit)...................... over there."
2. There (be) ………….. no rain here for 6 months.
3. He spoke to me as if he (be) ………… my father.
4. By the time we (stop) …………, we had driven six hundred miles.
5. The price ( become ) ................... more and more expensive these days.
6. Pupils are made (work)……………… hard at this school.
7. It’s ten years since I last (see) ………… her.
8. Don’t forget (lock) ………… the door before going to bed.
9. The pens ( produce ).............. by Thien Long Company are usually cheap and good.
10. The film (begin) ......................at 7.30 or 8.00?
IV. Fill the blanks with the right form of the CAPITAL words provided in the right
column
1. Their children have quite _____________ characters. DIFFERENCE
2. What is the correct ______________of this word? PRONOUNCE
3. He didn’t win the championship, so he felt very _____________ . hope
4. She is one of the greatest _______ to appear in this theater. PERFORM
5. My house is on the top of a hill. It’s very ____ there in the fall. WIND
6. It is ___________ to eat too much sugar and fatty food. HEALTH
7. Many rural areas in Viet Nam have been __________ in the last few years. urban
8. Bell ______________ demonstrated his invention. SUCCESS
9. Every day, there are two ____ from Da Nang to Ho Chi Minh city. FLY
10. There are a lot of _______________ in the competition. contest
V. Choose the underlined words or phrases that are not corect in standard written
English. Find and correct it
1. Lan seemed happily when she received her aunt’s letter.
2. My brother didn’t have money enough to buy the dictionary he liked
3. We should put the coffee table among the armchair and the couch.
4. The driver of the car was serious injured in the accident.

5. Everyone was exciting as the prince wanted to choose his wife from the village.
6. He gets up early in order reviewing lessons before school.
7. All the students are looking forward to spend their free time relaxing in the sun this
summer.
8. I agree that we ought be good students at school and good children at home
9. Be careful when you cross a busy street. Look out with cars and trucks.
10. Is she accustomed to doing her homework by her?

I. Choose the correct answers in A, B, C or D to complete each sentence
1. Bob hasn’t ……… his mind yet.
A. made B. gone C. used to D. found
2. Everyone has to follow this way to get into the fair, ………?
A. do they B. don’t they C. doesn’t she D. doesn’t he
3. We spent half a year _____ this hotel.
A. to build B. built C. with building D. building
4. She is bored _____ getting up early.
A. with B. in C. of D. to
5. Would you like me to get you something to drink? - ______
A. That would be nice B. No, I’m sorry C. That’s too bad D. My pleasure
6. English is the _____ language on one- fifth of the land area of the world.
A. office B. official C. officer D. officially
7. It's an hour since he ......... , so he must be at the office now.
A. has left B. left C. was leaving D. is leaving
8. 14. I usually go to work by bus, but ________ and then I use my motorbike.
A. again B. Once C. now D. ever
9. Of my parents, my father is _________________.
A. the stricter B. the strictest C. stricter D. strict
10. "What can I get for you?". ______________ .
A. All right B. I'm afraid not C. I hope so D. Yes, please
II. Choose the word whose underlined part is pronounced differently from the
others.
1. A. think B. healthy C. thus D. ethnic
2. A. discussion B. revision C. attention D. admission
3. A. cease B. chase C. increase D. raise
4. A. although B. enough C. laugh D. cough
5. A. mute B. junior C. music D. humor
6. A. who B. where C. which D. when
7. A. send B. tent C. rely D. tend
8. A. lock B. shock C. block D. program
9. A. talked B. passed C. dialed D. stopped
10. A. comb B. climb C. dumb D. blond

SECTION III: WRITING

Question 1: Rewrite sentences as directed.
1. Why don’t you take that English course?
If.............................................................................................................................................
2. You forgot to turn off the TV last night, didn’t you?
You didn’t.....................................................................................................................................?
3. Despite his age, Mr. Thanh runs five kilometres every morning.
Even..............................................................................................................................................
4. He didn’t finish his work until the bell rang.
Not until.........................................................................................................................................
5. When he is asked about his past, he hates it.
He hates..........................................................................................................................................
6. Without Tom’s help, Bill couldn’t have finished the work.
If it..................................................................................................................................................
7. William said to Mary “Why don’t you put your luggage under the seat?”
William suggested..........................................................................................................................
8. “It’s time we went to bed” they said. (Rewrite, using reported speech)
.......................................................................................................................................................
9. The robbers made the bank manager hand over the money.

The bank manager ........................................................................................................................
10. She hasn’t been to Ho Chi Minh City for three years.
The last..........................................................................................................................................
11. I cleaned the floor then I went to bed.
After...............................................................................................................................................
12. “Don’t forget to send your parents my regards”, she said to me.
She told.........................................................................................................................................
13. “Would you like to dance with me?” she said to John.
She...............................................................................................................................................
Question 2: Write complete sentences using the words given to form a letter:
Dear Uncle Tom,
1. Thank / much / alarm clock / send me / 15th birthday.
.........................................................................................................................................................
2. It just / what / need.
........................................................................................................................................................
3. I / terrible / get up late / every morning.
.......................................................................................................................................................
4. Thanks / your present / I / wake up / time.
.......................................................................................................................................................
5. I / hope / you both well.
.....................................................................................................................................................
6. I / look forward / see / you / Christmas.
......................................................................................................................................................
7. Thanks also / lovely card.
......................................................................................................................................................

Question 1. Choose ONE appropriate question in the box to each paragraph below:

1/ How do industry and transport cause pollution?
2/ How can I help?
3/ What is the pollution?
4/ How can industry help?
5/ What cause pollution?
6/ What about air pollution?

A. ___ Pollution is the poisoning of the land, sea and air.
B. ___ Mainly industry and transport. If you go to any city, you will see too many
factories, too many cars with not enough people in them, and not enough public transport.
C. ___ Factories and vehicles produce waste which goes into the air and rivers and
spreads all over the land. Poisons in the waste build up over the years and harm trees,
plants, animals, and people.
D. ___ Waste gases build up in the air, and dissolve into raindrops, forming a weak
acid. This "acid rain" can fall far away from the country which produced it, killing trees in
forests and fish in lakes and rivers.

E. ___ If companies clean their waste gases before releasing them into the
atmosphere, there'll be much less air pollution and no acid rain. But this can be expensive
and it needs all the world's companies to do it.
F. ___ Cars pollute the atmosphere. Walk, cycle and use public transport as much as
possible. Only use your car when you really need to, and use unleaded petrol if you can -
lead is one of the most dangerous ingredients in petrol. Join us, and help us to campaign for
cleaner air for everybody.

Question 2: Match a verb in A with a phrase in B to have a completel phrase.:

A
0. to drink
1. to go
2. to look
3. to live
4. to provide
5. to watch
6. to fix
7. to have
8. to prefer
9. to need
10. to arrive

B
a. in an urban area
b. more money
c. the news
d. a meeting
e. at the station at 5.30
f. for suitable jobs in the city
g. the countryside to the city
h. facilities for the people
i. the computer
j. to the countryside in the weeked
k. a cup of tea

0-k 1-..... 2-..... 3-..... 4-...... 5-..... 6-...... 7-...... 8-...... 9-...... 10 -.......

II)
Complete the second sentence so that it has a similar meaning to the first
sentence.
1.People believe that 13 is an unlucky number.
13 is ………………………………………………….
2. “How many cars are there in front of your house, Mai?”
I asked …………………............................................
3.No one introduced me to newcomers in the festival.
I ……………………………………………………
4.The food was too bad for the children to eat.
The food was so ……………………………
5.It’s no use persuading her to join in that activity.
There is no ……………………………..