The Great Barrier Reef is the earth’s ___(23)___ reef system. At a length of over 2,500 km it is the largest ___(24)___ structure. You can even see it from space. However, the reef is in danger of dying. Because of global warming, the temperature in the atmosphere keeps rising. This also affects the water temperature. When the oceans get too warm the colorful reefs turn grey and die. The reef is also dying ___(25)___ pollution ___(26)___ by factories on the Australian and Indonesian coasts.
It’s a pity that we don’t care about the environment the ways the Aborigines did thousands of years ago. They respected nature, the animals and plants around them. They never killed more animals than they could eat. However, when Europeans arrived in Australia they destroyed a lot of things ___(27)___ the Aborigines valued.

Question 23.
A. largest 
B. large 
C. larger 
D. enlarge 
Question 24.
A. live 
B. living 
C. alive 
D. life 
Question 25.
A. of 
B. for 
C. to 
D. from 
Question 26.
A. to cause 
B. causing 
C. cause 
D. caused 
Question 27.
A. whose 
B. that 
C. whom 
D. who