D

  Forget humane removal. Scientists studying the giant Burmese pythons （蟒蛇）that invaded Florida have discovered the snakes can find their way home even when taken up to 20 miles away.

  The snakes homing ability is "previously undocumented for any snake species," said Shannon Pittman, a scientist at Davidson College in Davidson, N.C.

Researchers at Davidson and the U.S. Geological Survey caught six Burmese pythons in Florida and placed radio transmitters （发射器）in them. They then took them 13 to 20 miles away and released them. The snakes immediately headed back, taking "direct and striking" routes, instead of moving randomly across the wetlands, said Kristen Hart, a research ecologist with the USGS in Gainesville, Fla. It took the snakes 94 to 296 days to return but eventually they navigated to within 3 miles of their original capture locations in Everglades National Park. No one knew Burnese pythons were capable of homing. Researchers don't know how the snakes do it. It could be by sight or smell or even the Earth's magnetic field.

The research shows that moving the snakes won't work as a control strategy. "You can't move them. Quite honestly, they're going to move back to where they came from," Hart said.

 Burmese pythons are one of the world's largest snakes. They are hard to spot in the grass even when tracked with transmitters. Native to southern Asia, the snakes began to appear in south Florida in the late 1990s, probably released by pet owners. They have since colonized hundreds of square miles in southern Florida, including  most of Everglades National Park and Big Cypress National Preserve.

While more than 2,000 Burmese pythons have been removed from the area since 2002, the National Park Service estimates that represents only a small part of the total population. "There are records of snakes up nearly to Lake Okeechobee," said Michael Dorcas, a biology professor at Davidson College. "Most scientists agree that they are likely well north of Alligator Alley now."

The snakes are devastating invaders, eating a wide variety of animals including deer and even crocodiles. "They're eating through the food chain," Hart said.

1.What is the main idea of the passage?

A Burmese pythons are really devastating invaders.

B Burmese pythons are able to find their way home.

C Burmese pythons have colonized most of Florida.

D Burmese pythons are famous for their big sizes.

解析：选B。主旨大意题。根据本文的主题句Scientists studying the invasive giant Burmese pythons（蟒蛇） that invaded Florida have discovered the snakes can find their way home even when taken up to 20 miles away可知本文主要讲缅甸蟒蛇具有非同寻常的导航本领，能找到回家的路。故B项最佳。

2.How did the released pythons return home?

A By taking direct and striking routes.

B By moving randomly across the wetlands.

C By winding their ways on the grass.

D By following the signs they had made.

解析：选A。细节理解题。根据第三段第三句The snakes immediately headed back, taking "direct and striking" routes, instead of moving randomly across the wetlands可知这些放生的缅甸蟒蛇是走捷径返家的。

3.What do you know about Burmese pythons?

A They are the world's largest snakes.

B They are easy to find in the grass.

C They are native to Southeast Asia.

D They entered south Florida in the late 1990s.

解析：选D。 细节理解题。根据第五段第三句the snakes began to appear in south Florida in the late 1990s 可知缅甸蟒蛇是在20世纪90年代末才侵入佛罗里达南部的。根据Burmese pythons are one of the world's largest snakes可知A项错误。根据They are hard to spot in the grass even when tracked with transmitters可知B项错误。根据Native to southern Asia可知C项错误。

4.We can infer that ______.

A more than 2,000 Burmese pythons live in south Florida

B many Americans raise Burmese pythons as their pets

C the python population in Florida needs to be controlled

D Burmese pythons can help us to protect other animals

解析：选C。推理判断题。根据最后两段While more than 2,000 Burmese pythons have been removed from the area since 2002, the National Park Service estimates that represents only a small part of the total population/The snakes are devastating invaders等信息我们可以得出结论：缅甸蟒蛇现在在佛罗里达泛滥成灾，破坏生态，到了该抑制缅甸蟒蛇数量的时候了。