iV .

1 on

2 for

3. of

4.off

5 into

V:

1.the

2.the

3.X

4.an

5.X

VII:

1.visited 

2.was

3.eating

4.is

6. B
7. D
8. C
9. A
10. A
11. A
12. A
13. A
14. B
15. C
16. B
17. C
18. A
19. C
 

1.D

2. C

1. D 

2. C

III.
A.
1.T
2.F
B.
1.Local people and tourists from all over the world attend the White Night.
2.People can see the raising of the bridges along the Neva River banks.
3.They go swimming in Lake Ladoga.
Part D. Writing:
I.
2.People won't use flying cars until the year 2050.
3.We will use more solar energy in the future.
4.Life must be difficult in the slums.
5.The beaches in the south are so peaceful.
II.
1.That chair is more comfortable than this one.
2.My mother used to live in a village when she was a girl.
3.Peter is interested in carving eggshells.
4.A hydro power will be built in this area next year.
5.In spite of being young, he performs exellently.

D=\(\frac{2}{1.4}+\frac{2}{4\cdot7}+...+\frac{2}{97\cdot100}\)

\(\frac{3}{2}D=\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{97\cdot100}\)

\(\frac{3}{2}D=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\)

\(\frac{3}{2}D=1-\frac{1}{100}=\frac{99}{100}\)

D=\(\frac{99}{100}:\frac{3}{2}=\frac{33}{50}\)

3/2D=3/1.4+3/4.7+3/7.10+........+3/97/100

==>3/2D=1/100

==>D=1/150

ko biết đúng hay sai

D = \(\frac{1}{3}.\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+....+\frac{3}{97.100}\right)\)

D = \(\frac{1}{3}.\left(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{97.100}\right)\)

D = \(\frac{1}{3}.\left(\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{97}-\frac{1}{100}\right)\)

D = \(\frac{1}{3}.\left(\frac{1}{1}-\frac{1}{100}\right)\)

D = \(\frac{1}{3}.\frac{99}{100}\)

D = \(\frac{33}{100}\)

đúng nhớ k nha