Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Her boyfriend is said _________ in the army two years ago.
A.have served
B.to have served
C.to serve
D.serving

Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
______ broken several world records in swimming.
A.It is said to have
B.She is said to have
C.People say she had
D.She is said that she has

Đa thức $ M $ nào dưới đây thỏa mãn tổng của M và đa thức: $ {{x}^{3}}+3{{x}^{2}}y-5x{{y}^{2}}-7xy-2 $ là một đa thức bậc 0.
A. $ M=-{{x}^{3}}-3{{x}^{2}}y+5x{{y}^{2}}+7xy. $
B. $ M=-{{x}^{3}}-3{{x}^{2}}y+5x{{y}^{2}}-7xy. $
C. $ M=-{{x}^{3}}-3{{x}^{2}}y-5x{{y}^{2}}+7xy. $
D. $ M=-{{x}^{3}}+3{{x}^{2}}y+5x{{y}^{2}}+7xy. $

Rút gọn biểu thức $ \left( 6,7x{{y}^{2}}-2,7xy+5{{y}^{2}} \right)-\left( 1,3xy-3,3x{{y}^{2}}+5{{y}^{2}} \right)$ ta được
A. $ -10x{{y}^{2}}-4xy. $
B. $ 10x{{y}^{2}}+4xy. $
C. $ 10x{{y}^{2}}-4xy. $
D. $ -10x{{y}^{2}}+4xy. $

Cho hai đa thức $ M={{x}^{2}}-2xy+{{y}^{2}} $ và $ N=4{{x}^{2}}-{{y}^{2}}-xy+1 $ . Kết quả của $ M-~N $ là
A. $ -3{{x}^{2}}-xy+2{{y}^{2}}-1 $ .
B. $ 3{{x}^{2}}-xy+\dfrac{5{{y}^{2}}}{3}-1 $ .
C. $ -3{{x}^{2}}-xy+2{{y}^{2}} $ .
D. $ -3{{x}^{2}}-xy+{{y}^{2}}-1 $ .

Rút gọn biểu thức $ \left( {{x}^{2}}+{{y}^{2}}-2xy \right)-\left( {{x}^{2}}+{{y}^{2}}+2xy \right)+\left( 4xy-1 \right)$, ta được
A. $ 2{{x}^{2}}+2{{y}^{2}}+8xy+1. $
B. $ -1. $
C.0.
D.1.

Cho hai đa thức: $ M=3,5{{x}^{2}}y-2x{{y}^{2}}+1,5{{x}^{2}}y+2xy+3x{{y}^{2}} $
Thu gọn đa thức $ M $ ta được
A. $ 5{{x}^{2}}y+x{{y}^{2}} $ .
B. $ -5{{x}^{2}}y+x{{y}^{2}}+2xy $ .
C. $ 5{{x}^{2}}y+x{{y}^{2}}+2xy $ .
D. $ 5{{x}^{2}}y-x{{y}^{2}}-2xy $ .

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Dinosaurs are thought to________millions of years ago.
A.having died out
B.dying out
C.die out
D.have died out

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Twenty workers are reported _______ in the explosion.
A.to injure
B.to be injured
C.to have injured
D.to have been injured

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
"Your kitchen is fantastic! Did you do it all by yourself?" –"No, I ______ by a professional."
A.have it to be designed
B.had designed it
C.had it designed
D.designed it