Reading passages

According to the passage, the threat of some certain substances to the environment
_________. 
A) is for less than that to man 
B) could be reduced by enforcing emission limits and environmental controls 
C) has been unnecessarily over emphasized 
D) has to date been completely ignored 
E) can be eliminated by the use of industrial waste streams 
53. 
The author assumes that the danger posed to man by some substances________. 
A) is even greater than generally admitted 
B) is unrelated to environmental pollution 
C) continues to grow despite constant control of disposal systems 
D) is solely due to the use of industrial waste streams 
E) arises from their misuse and wrong disposal 
54. The passage is concerned with the question of 
. 
A) how the harmful effects of certain substances can be kept under control 
B) why industrial waste streams have led to so much pollution 
C) what measures are to be taken against the supply of dangerous substances 
D) if man-made substances and natural ones cause pollution 
E) who is responsible for taking the required precautions 
The cheetah, the only mammal in the world that can sprint at spee faster than 70 miles per hour, is on 
rapid track to extinction. Two factc threaten its existence. The first is lack of genetic variation, which 
manife; itself in reproductive problems excessive infant mortality and vulnerability disease. These 
seem to be exacerbated in captivity, where cheetahs i experiencing a precipitous decline in number. 
The second threat to t cheetah is loss of its natural habitat to agricultural expansion. 
55. 
The cheetah is the only mammal in the world that 
. 
A) threatens the nature 
B) is in danger of extinction 
C) no other animals can reach its speed 
D). has a speed reaching more than 70 miles per hour 
E) is thought to give harm to agricultural expansion