5. She took _____ playing the piano when she was a young girl

A. in

B. over

C. up

D. on

6. ___________ is her father’s hobby. He s going to the zoo to see beautiful parrots or canaries.

A. Collecting birds

B. Bird - watching

C. Raising pets

D. Arranging flowers

7. It’s interesting ______ a puppy. I enjoy _____ after it very much.

A. having/ looking

B. having/ to look

C. to have/ to look

D. to have/ looking

8. One of my favorite hobbies is ______ comics. I love _______ more famous ones.

A. read/ collecting

B. reading/ collecting

C. to read/ to collect

D. reading/ collected

9. The bus ______ in two minutes. I _____ late for school when I _____ it.

A. arrives/ will be/ miss

B. will arrive/ will be/ miss

C. arrives/ am/ will miss

D. will arrive/ am/ will miss

10. I love making ___________ because I can create some nice and unique clay bottles or cups to give my friends.

A. pottery

B. paper kites

C. architectures

D. lanterns

5. She took _____ playing the piano when she was a young girl

A. in

B. over

C. up

D. on

6. ___________ is her father’s hobby. He s going to the zoo to see beautiful parrots or canaries.

A. Collecting birds

B. Bird - watching

C. Raising pets

D. Arranging flowers

7. It’s interesting ______ a puppy. I enjoy _____ after it very much.

A. having/ looking

B. having/ to look

C. to have/ to look

D. to have/ looking

8. One of my favorite hobbies is ______ comics. I love _______ more famous ones.

A. read/ collecting

B. reading/ collecting

C. to read/ to collect

D. reading/ collected

9. The bus ______ in two minutes. I _____ late for school when I _____ it.

A. arrives/ will be/ miss

B. will arrive/ will be/ miss

C. arrives/ am/ will miss

D. will arrive/ am/ will miss

10. I love making ___________ because I can create some nice and unique clay bottles or cups to give my friends.

A. pottery

B. paper kites

C. architectures

D. lanterns

Ta có 

\(\frac{a_1}{a_2}+\frac{a_2}{a_3}+...+\frac{a_{2008}}{a_1}=\frac{a_1+...+a_{12}+...+a_{2008}}{a_2+a_3+...+a_1}=1\)

Từ đó a₁ = a₂ = a₃ = ... = a₂₀₀₈

\(\Rightarrow N=\frac{a^2_1+a^2_2+...+a_{2008}^2}{\left(a_1+a_2+...+a_{2008}\right)^2}=\frac{2008a^2_1}{\left(2008a_1\right)^2}=\frac{1}{2008}\)

alibaba mình nghĩ là thay dấu + là dấu = sẽ đúng hơn