(1)
A)It limited their supply of food.
B)It made their eggshells too fragile.
C)It destroyed many of their nests.
D)It killed many baby bald eagles. (2)
A)They found ways to speed up the reproduction of bald eagles.
B)They developed new types of feed for baby bald eagles.
C)They explored new ways to hatch baby bald eagles.
D)They brought in bald eagles from Canada. (3)
A)Pollution of the environment
B)A new generation of pest killers.
C)Over-killing by hunters.
D)Destruction of their natural homes.
原文：
Passage Two
America's national symbol, the bald eagle, almost went extinct twenty years ago, but it has made a comeback. In fact, the U.S. Fish and Wild Life Service is considering the possibility of taking it off the Endangered Species List. Once, more than fifty hundred pairs of bald eagles nested across the country, but by 1960 that number had fallen below four hundred. The chief killer was the widely used DDT. Fish, soaked up DDT, died, and were washed up on shores, where bald eagles feasted on them.?DDT prevented eagle egg shells from thickening. The shells became so thin that they shattered before the babies hatched. Fortunately, in 1972, a law was passed to ban DDT, which saved the bald eagle from total wipeout. And since then wild life biologists had reintroduced bald eagles from Canada to America. The result was that last year U.S. bird watchers counted eleven thousand six hundred and ten bald eagles in the country.?If it were dropped from the Endangered Species List, the bald eagle would still be a threatened species. That means the bird would continue to get the same protection. No hunting allowed, and no disturbing of nests. But bald eagles still face tough times. The destruction of their natural homes could be the next DDT causing eagle numbers to drop quickly.?
Question 14: What was the main harmful effect of the pests killer DDT on bald eagles?
Question 15: What measure did the wild life biologist take to increase the number of bald eagles?
Question 16: According to the speaker, what is the possible danger facing bald eagles?