Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
The editor asked Nam to write some practical advice on the ………. of the environment.
A.preserved
B.preservation
C.preserving
D.preserve

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Most of the air pollution results ………. the burning of fossil fuels, motor vehicles, factories, aircrafts and rockets.
A.of
B.from
C.to
D.in

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Rainforests are valuable habitats for species of wild animals and………...
A.vegetate
B.vegetation
C.vegetarian
D.vegetative

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
The World Wide Fund for Nature ………. set up in 1961.
A.is
B.has been
C.was
D.is being

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
Rising sea levels can add to the ………. of our coastlines.
A.erosion
B.eroded
C.erosional
D.erode

Cho hai đa thức: $ M=3,5{{x}^{2}}y-2x{{y}^{2}}+1,5{{x}^{2}}y+2xy+3x{{y}^{2}} $
$ N=2{{x}^{2}}y+3,2xy+x{{y}^{2}}-4x{{y}^{2}}-1,2xy $
Giá trị của biểu thức $ M-N $ tại $ x=-1;\text{ }y=-2 $ là 
A. $ 22 $ .
B. $ -22 $ .
C. $ -21 $ .
D. $ 20 $ .

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

Cho $ P=2{{x}^{2}}-3xy+4{{y}^{2}};~\,\,Q=3{{x}^{2}}+4xy~-\text{ }{{y}^{2}};\text{ }R={{x}^{2}}+2xy+3{{y}^{2}} $ . Đa thức $ P-~Q-R $
A. $ -2{{x}^{2}}-9xy+2{{y}^{2}} $
B. $ -{{x}^{2}}-9xy+2{{y}^{2}} $
C. $ {{x}^{2}}-7xy+{{y}^{2}} $
D. $ 2{{x}^{2}}-9xy+2{{y}^{2}} $

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

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to the following question.
………. pollution is one of the impacts of human activities on the Earth.
A.Environmental
B.Environmentalist
C.Environmentally
D.Environment