Tính:

a)  6 3 1 : 6 2 1

b)  7 2 1 2 : 7

c)  2018 2 0 1 8 : 1 2018

Viết kết quả của phép tính dưới dạng một lũy thừa:

a)  9 2 : 3 2

b)  125 : 5 2

c)  x m + n : x n   ( x ≠ 0 ; m , n ∈ N )

d)  y 2 m : y m   ( y ≠ 0 ; m ∈ N )

Trùng hợp stiren thu được polistiren có khối lượng mol bằng 312000 gam. Hệ số trùng hợp của polistiren là:

A. 2575                      

B. 2750                         

C. 3000                          

D. 3500

Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

I was offered to work for IBM, but I rejected.

A. I rejected to offer to work for IBM.

B. I was refused by IBM at work.

C. I turned down the offer to work for IBM. 

D. IBM refused my offer to work.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

"Why don't you have your room repainted?" said Robert to Lan.

A. Robert suggested having Lam's room repainted.

B. Robert asked Lam why you didn't have your room repainted.

C. Robert wanted to know why Lam doesn't have his room repainted,

D. Robert suggested that Lam should have his room repainted.