Chứng minh giá trị biểu thức sau không phụ thuộc vào giá trị của biến:

(x − 5)(2x + 3) − 2x(x − 3) + x + 7.

Tìm x, biết: (12x − 5)(4x − 1) + (3x − 7)(1 − 16x) = 81.

1. MULTIPLE CHOICES

A. Choose the word which has the underlined part pronounced different from that of the others.

1. A. arrange           B. happy                 C. match                 D. candle                   

2. A. precaution       B. member              C. electric               D. chemical

B. Choose the word which has the different stress pattern

1. A. wardrobe        B. cupboard            C. saucepan            D. between                 

2. A. precaution       B. vegetable            C. opposite             D. medicine

C. Choose the correct answers:

1. As a student, you _____ hard to please your parents.

A. ought to working B. ought working     C. ought to work      D. ought work                   

2.It is safe ___ medicine in locked cupboard.

A. putting               B. to put                 C. put                     D. puts                            

3.The children are old enough to take care of _______.

A. ourselves            B. himself               C. myself                D. themselves                   

4.You must cover all _______ socket in your house.

A. electrical            B. electrify              C. electricity           D. electrician          

5.Don’t let your little brother play with ballpoint pen. They can _____ him.

A. injure                 B. destroy               C. take                    D. put                    

6.You have to keep all dangerous objects ______ children’s reach.

A. from                   B. for                      C. out of                 D. of                      

7. They arrived home ___________ after a long distance journey.

A. safety                 B. safe                    C. safely                 D. unsafe

8. Heat gradually ________________ Vitamin C

A. destruction          B. destroy               C. destroying          D. destroys

9. Don’t leave the light on. It waste ______________

A. electrical            B. electricity           C. electric               D. electrician

10. Every year, factories release thousands of tons of poisonous ____________into the atmosphere

A. chemical             B. chemicals           C. chemist              D. chemistry

11. Kitchen is an ________________ place to play.

A. suitable              B. suitably              C. unsuitable           D. unsuitably