Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

___________ is to give strangers your address.

A. What must never you do

B. That must never you do 

C. That you must never do

D. What you must never do

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

__________, no one was absent from the farewell party last night.

A. Heavily as it rained

B. As it rained heavily 

C. Though it rains heavily

D. In spite of the heavily rain

Mình nghĩ là bài 1: 2/141 đổi thành 2/143 mới đúng đề nha.

Bài 1: Tham khảo https://olm.vn/hoi-dap/question/40337.html

A= \(\dfrac{2^2}{1.3}+\dfrac{2^2}{3.5}+...\dfrac{2^2}{99.101}\)

= \(\dfrac{4}{1.3}+\dfrac{4}{3.5}+...+\dfrac{4}{99.101}\)

= \(\dfrac{4}{2}.\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{99}-\dfrac{1}{101}\right)\)

= \(2.\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{99}-\dfrac{1}{101}\right)\)

= \(2.\left(\dfrac{1}{1}-\dfrac{1}{101}\right)\)

= \(2.\dfrac{100}{101}\)

= \(\dfrac{200}{101}\)

A= \(\dfrac{3}{3.5}+\dfrac{3}{5.7}+\dfrac{3}{7.9}+...+\dfrac{3}{97.99}\)

= \(\dfrac{3}{2}.\left(\dfrac{1}{3.5}+\dfrac{1}{5.7}+\dfrac{1}{7.9}+...+\dfrac{1}{97.99}\right)\)

= \(\dfrac{3}{2}.\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{97}-\dfrac{1}{99}\right)\)

= \(\dfrac{3}{2}.\left(\dfrac{1}{3}-\dfrac{1}{99}\right)\)

= \(\dfrac{3}{2}.\dfrac{32}{99}\)

= \(\dfrac{3.32}{2.99}\)= \(\dfrac{3.2.3.6}{2.11.3.3}\)= \(\dfrac{6}{11}\)

B)

B = \(\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{29.31}\)

= \(\dfrac{1}{2}.\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...\dfrac{1}{29.31}\right)\)

= \(\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{29}-\dfrac{1}{31}\right)\)

= \(\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{31}\right)\)

= \(\dfrac{1}{2}.\dfrac{30}{31}\)

= \(\dfrac{30}{62}\) = \(\dfrac{15}{31}\)