chứng minh:

a) (x-1)(x+1)=x²-1

b) (x+1)(x²-x+1)=x³

c) (x+y)(x+y)=x²+2xy+y²

cho △ABC cân tại A, 

cho ∆ABC cân tại A, A^ >90° các đường trung trực của AB,AC cắt nhau tại O và cắt BC tại D và E chứng minh:

a) OA là dường trung trực của BC

b) BD=CE

c) ∆ODE là ∆ cân

4. What is the distance between Thanh Hoa and Ha Noi city?
How far.....................................................................................................?
5. I often walked to school when I was a student.
 I used........................................................................................................
6. In spite of being so young, Tien Dung goalkeeper performs excellently.
Although.................................................................................................
7. What is the distance between Vinh and Ha Noi city?
 How.........................................................................................................?
8. I often walked to school when I was a student.
I used.......................................................................................................
9. Although they are short, they still love playing sports.
 In spite of................................................................................................
10. We will use less electricity in the future
 Less electricity ........................................................................................

16.My mother ( not like ) ______________________ riding a motorbike.
17.When my father was young, he (drink ) _____________________ a lot of beer.
18.Nam ( study ) ______________________ homework in the living room now.
19.Be careful ! The car ( come ) ______________________ .
20.My mother ( go ) ______________________ to the supermarket yesterday evening.
21.Nam ( play) ________________________ soccer tomorrow.
22. By 2020, people in Viet Nam (spend) _____________________ a lot of money on heating.
23. What_____________we (do ) ____________________ to save electricity ,dad ?
We will watch less TV.
24. At 10 o’clock tomorrow he ( work ) _____________________ in his office.
25. My father ( visit ) ____________________ to Ha Long Bay next week.
26.At 5 o’clock tomorrow Nam ( play) ________________________football with his friends.
27.They ( build) _____________________ their house this time next week.
28.At 8 a.m tomorrow, my sister (learn ) _____________________ English with her friends.
29.Ba ( buy ) ____________________ a new house tomorrow.
30.We ( build) ________________________ a hydro power station in this area next month.

1.Nam often ( play) ________________________ soccer in the afternoon.
2.My father used to (go) _____________________swimming when he was a child.
3.What about ( go) ____________________ to the zoo on Sunday evening ?
4. Tien Dung goalkeeper ( live ) _____________________ Thanh Hoa city since 1997.
5.I used to ( go) ____________________ to the zoo on Sundays when I was a child.
6.Xuan Truong footballer ( play) ________________________ soccer beautifully last Saturday.
7.Nam used to (go) _____________________fishing when he was a child.
8.They (learn ) _____________________ English for five years.
9.How about ( go) ____________________ to the zoo on Sunday evening ?
10.Quang Hai footballer ( play) ________________________ soccer beautifully last Saturday.
11.I ( meet ) ______________________ her at the movie theater last night.
12.He ( go ) ___ to the English club every Sunday. But last Sunday he ( not go ) ________ there, he went to the City’s
museum.
13.Two years ago, she ( teach ) ______________________ at a village school.
14.What __________you (do) ____________ yesterday morning?
15.We ( travel ) ______________________ to Hue next month.

II. Put the correct form of the verb in brackets.
( Chia dạng đúng của động từ trong ngoặc )
1.Nam often ( play) ________________________ soccer in the afternoon.
2.My father used to (go) _____________________swimming when he was a child.
3.What about ( go) ____________________ to the zoo on Sunday evening ?
4. Tien Dung goalkeeper ( live ) _____________________ Thanh Hoa city since 1997.
5.I used to ( go) ____________________ to the zoo on Sundays when I was a child.
6.Xuan Truong footballer ( play) ________________________ soccer beautifully last Saturday.
7.Nam used to (go) _____________________fishing when he was a child.
8.They (learn ) _____________________ English for five years.
9.How about ( go) ____________________ to the zoo on Sunday evening ?
10.Quang Hai footballer ( play) ________________________ soccer beautifully last Saturday.
11.I ( meet ) ______________________ her at the movie theater last night.
12.He ( go ) ___ to the English club every Sunday. But last Sunday he ( not go ) ________ there, he went to the City’s
museum.
13.Two years ago, she ( teach ) ______________________ at a village school.
14.What __________you (do) ____________ yesterday morning?
15.We ( travel ) ______________________ to Hue next month.
16.My mother ( not like ) ______________________ riding a motorbike.
17.When my father was young, he (drink ) _____________________ a lot of beer.
18.Nam ( study ) ______________________ homework in the living room now.
19.Be careful ! The car ( come ) ______________________ .
20.My mother ( go ) ______________________ to the supermarket yesterday evening.
21.Nam ( play) ________________________ soccer tomorrow.
22. By 2020, people in Viet Nam (spend) _____________________ a lot of money on heating.
23. What_____________we (do ) ____________________ to save electricity ,dad ?
We will watch less TV.
24. At 10 o’clock tomorrow he ( work ) _____________________ in his office.
25. My father ( visit ) ____________________ to Ha Long Bay next week.
26.At 5 o’clock tomorrow Nam ( play) ________________________football with his friends.
27.They ( build) _____________________ their house this time next week.
28.At 8 a.m tomorrow, my sister (learn ) _____________________ English with her friends.
29.Ba ( buy ) ____________________ a new house tomorrow.
30.We ( build) ________________________ a hydro power station in this area next month.

15. ____________ is not very far from here to the harbour.
A.There B. It C. This D.That
16.The boys _______ home for lunch because they are planning to visit the hydro power station.
A. have not come B. do not come C. will not be coming D. is not coming
17.It is going to rain any minute now. The children ___________ in the rain.
A. is being caught B. will be caught C. is caught D. are caught
18.They ___________ a test tomorrow; we don’t want to disturb them.
A. will be having B. will have C. have D. had
19.They ___________ that we have gone without telling them.

A. thought B. are thinking C. will be thinking D. think
20. The sun and the wind are other ____________sources of energy.
A. alternative B. renewable C. non-renewable D. Nuclear
21.We _____ solar panels in the schoolyard while you are checking cracks in the water pipes.
A. have put B. will be putting C. will put D. put
22.At 7.00 tomorrow, you ___________ to school.
A .cycle B. will cycle C. will be cycling D. will be cycled
23.Solar energy ___________ by many countries in the world in the future.
A. use B. will use C. will be using D. will be used
24.At this time tomorrow, I ________ an interview.
A. will be having B. will have C. had D. have
25. Coal is a __________ energy.
A. nuclear B. solar C. biogas D. natural
26. We should __________ low energy light bulbs.
A. use B. using C. used D. to use
27. The wind turns __________ to make electricity.
A. fans B. leaves C. turbines D. kites
28. We ________ an English test tomorrow.
A. will have B. have C. has D. had
29. Solar energy will ________ to solve the problem of energy shortage.
A. use B. be used C. used D. using
30.You should turn ________ the lights when leaving the rooms.
A. on B. off C. right D. left