paragraph The Bald Eagle

　　1 When the bald eagle became the national symbol of the United States in 1782, soon after the country was born, it is estimated that there were as many as 75,000 nesting pairs in North America. By the early 1960s, however, the number of nesting pairs had been reduced to only around 450.

　　2 The demise of the bald eagle is generally attributed to the effects of the pesticide DDT (dichloro-diphenyl-trichloroethane). This pesticide was used to kill insects harmful to agriculture, thereby increasing agricultural production. One unintended negative result of the use of DDT was that, while it did get rid of the undesirable insects, it also made its way along the food chain into fish, a favorite food source of the bald eagle.

　　3 The bald eagle is now protected by federal laws. It was originally protected by the Bald Eagle Act of 1940 and later by the Endangered Species Act of 1973. However, it is not just the laws directly related to endangered species that aided in the resurgence of the bald eagle; its resurgence has also been widely attributed to the banning of DDT in 1972. Today there are more than 5,000 pairs of bald eagles, a tenfold increase over the low point of 450, and the bird was removed from the list of endangered species in july, 1999.

　　Answer Choices (choose 4 to complete the chart):

　　(1) the numbers of bald eagles were greatly reduced, at least in part due to the effects of a pesticide.

　　(2) The legislation has had a positive effect on the number of bald eagles.

　　(3) The bald eagle was named as the national symbol of the United States in the late eighteenth century.

　　(4) Early in the history of the United States, there were huge numbers of bald eagles.

　　(5) Two different pieces of legislation that affected the bald eagle were enacted 33 years apart.

　　(6) The federal government enacted legislation specifically designed to protect the bald eagle as well as to outlaw the pesticide DDT.

　　参考答案：(1)、(2)、(4)、(6)