* Mark the letter A, B, C or D on your answer sheet to indicate the word whose differs from the other three in stress in each of the following questions.

A. believe

B. marriage

C. maintain

D. response

Đặt A=90+110+132+...+930

=9.10+10.11+11.12+...+30.31

=>3A=3.9.10+3.10.11+...+3.30.31

=9.10.11-8.9.10+10.11.12-9.10.11+....+30.31.32-29.30.31

=30.31.32-8.9.10

=29040

=>A=29040:3=9680

a)6,3+(-3,7)+2,4+(-0,3)=[6,3+2,4]+[(-3,7)+(-0,3)]=8,7+(-4)=8,7-4=4,7

b)(-4,9)+5,5+4,9+(-5,5)=[(-4,9)+4,9]+[5,5+(-5,5)=(4,9-4,9)+(5,5-5,5)=0+0=0

c)2,9+3,7+(-4,2)+(-2,9)+4,2=3,7+[2,9+(-2,9)]+[4,2+(-4,2)]=3,7+(2,9-2,9)+(4,2-4,2)=3,7+0+0=3,7

d)(-6,5).2,8+2,8.(-3,5)=2,8.[(-6,5)+(-3,5)]=2,8.(-10)=(-28)