题目内容：

A dragonfly barely an inch and a half long appears to be animal world’s most productive long distance traveler - flying thousands of miles over oceans as it migrates from continent to continent - according to a newly published research.

Biologists who led the study say the evidence is in the genes. They found that populations of this dragonfly, called Pantala flavescens, in Texas, eastern Canada, Japan, Korea, India, and South America, have genes so similar that there is only one likely explanation. Apparently — somehow — these insects are traveling distances that are extraordinarily long for their small size, breeding (繁殖) with each other, and creating a common worldwide gene pool.

But how do insects from different continents manage to meet and hook up? Ware says it appears to be the way their bodies have evolved. “These dragonflies have adaptations such as increased surface areas on their wings that enable them to use the wind to carry them.”

Dragonflies, in fact, have already been observed crossing the Indian Ocean from Asia to Africa. “They are following the weather,” says Daniel Troast, who analyzed the DNA samples in Ware’s lab. “They’re going from India where it’s dry season to Africa where it’s wet season, and apparently they do it once a year.”

Wetness is a must for Pantala to reproduce, and that, says Ware, is why these insects would be driven to even attempt such a dangerous trip, which she calls a “kind of suicide.” The species depends on it. While many will die on the route, as long as enough make it, the species survives.

For the moment, the details of this extraordinary insect travel are an educated best guess. Much more work is needed to bring many loose ends together. Ware and Troast hope that scientists can work on plotting those routes.

1.What proves Pantala flavescens are the world’s longest-distance flyers?

A. Scientists have tracked the dragonfly across the world.

B. There are many Pantala flavescens in various continents.

C. The same dragonfly was found both in Asia and America.

D. Pantala flavescens in different continents have similar genes.

2.What helps Pantala flavescens fly over so long distance?

A. Their special body shape.

B. Their ability to use wind.

C. Their small and light body.

D. Their large and strong wings.

3.What is necessary for Pantala flavescens to reproduce?

A. Damp weather.    B. Enough sunshine.

C. Dry environment.    D. Warm nests.

4.What does the underlined word “it” in Paragraph 5 refer to?

A. The weather.    B. The insect.

C. The wind.    D. The trip.