Exercise 5. Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 21 to 25.
Polar bears are in danger of dying out. Unlike some other endangered animals, it's not hunters that are the problem, it's climate change. Since 1979, the ice cap at the Arctic Circle where the polar bears has reduced in size (21)_________ about 30 per cent. The temperature in the Arctic has slowly been rising and this is (22)_________  the sea ice to melt, endangering the polar bears' home. The polar bears' main sources of food are the different types of seals found in the Arctic. They catch them by waiting next to the air holes seals have made in the ice. (23)_________  the bears are very strong swimmers, they could never catch seals in water. This means that the bears really do rely on the ice to hunt.
Polar bears also need sea ice to travel. They can cover a huge territory and often swim from one part of the ice to another. They have been (24)_________  to swim up to 100 km, but when there is less ice, they may have to swim further and this can (25)_________  fatal to the bears. A number of bears have drown in the last few years and scientists believe that it is because they were not able to reach more ice before they became too tired and couldn't swim any further.
(24) 
A.known                    
B.learnt                       
C.experienced            
D.noticed

(28) 
A.When                      
B.Second                    
C.Finally                    
D.Firstly

________(72) 
A.precise
B. right
C.true 
D.valid

Coming unexpectedly into the room,_____
A.so she made the intruder get surprised
B.her appearance took the intruder a surprise
C.it surprised the intruder with her appearance
D.she took the intruder a surprise

Mark the letter A, B, C or D to indicate the word that differs from the rest in the position of the main stress in each of the following questions.

A.ashtray                    
B.music                      
C.severe                     
D.temper

John: “Do you think that we should use public transportation to protect our environment?” Laura: "______"
A.Of course not. You bet.
B.Well, that’s very surprising.
C. There is no doubt about it.
D.Yes, it’s an absurd idea.

In the fourth paragraph, the author implies that imagination is most important to scientists when they________.
A.formulate possible solutions to a problem 
B. evaluate previous work on a problem
C.close an investigation  
D. gather known facts

A.capital
B.tradition
C.different
D.opera

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions
It is very difficult to _______ the exact meaning of an idiom in a foreign language.
A.exchange      
B.transfer 
C.convert
D.convey

………air is essential to man, so is water to fish.
A. As 
B.Just 
C.Since    
D. Like