1.My brother isn't very sporty .He usually stays at home to read book in the afternoon.

2.What is your favourite subject at school ?

3.How many times a day do you brush your teeth ?

4.In Electronics ,they learn to repair household appliances.

5.The most popular activity at recess is talking.

6.Hoa is having a medical check-up.

7.The nurse wanted to know Nga's height and weight .

8.I'd like a nice juicy orange.

9.I have less time to play than my friends.

10.Edison's most famous invention (sự phát minh) was the electric bulb.

GOOD LUCK!!!!^-^

Ta có:

\(\frac{1}{5}+\frac{-1}{6}+\frac{1}{7}+\frac{-1}{8}+\frac{1}{9}+\frac{1}{8}+\frac{-1}{7}+\frac{1}{6}+\frac{-1}{5}\)

=\(\left(\frac{1}{5}+\frac{-1}{5}\right)+\left(\frac{-1}{6}+\frac{1}{6}\right)+\left(\frac{1}{7}+\frac{-1}{7}\right)+\left(\frac{-1}{8}+\frac{1}{8}\right)+\frac{1}{9}\)

=\(\left(\frac{-1+1}{5}\right)+\left(\frac{-1+1}{6}\right)+\left(\frac{-1+1}{7}\right)+\left(\frac{-1+1}{8}\right)+\frac{1}{9}\)

=\(\frac{0}{5}+\frac{0}{6}+\frac{0}{7}+\frac{0}{8}+\frac{1}{9}\)

=\(\frac{1}{9}\)

1.A

2. B

3. B

4. D

5. A

6. A

7. A

8. C

9. B

10. B

Chúc bạn học tốt !☆☆☆☆☆☆☆☆☆☆☆☆☆