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Many science fiction stories tell about explorers arriving in a new world who use some kind of high-tech device to test for breathable air or signs of life. But here on Earth, science fiction is becoming reality through a new sampling technology called environmental DNA (eDNA). Scientists can use it to identify rare species, or estimate fish populations with just a little air or water. Scientists study the genetic material released by living creatures. Essentially they can take a sample of soil, air or water, and they can sequence (排序) the DNA out of it and tell you what is there.

EDNA can be used to identify the creatures that live in a certain place. Besides, it can confirm the presence or lack of a specific creature. The cost of gene sequencing has reduced greatly in recent years, which makes DNA testing more widely available

Caren Goldberg, who heads the new eDNA lab at Washington State University, is one of the first biologists to take the technology from the testing period to actually using it.

“It is extremely useful for species that are really hard to find. I have spent many hours looking for species that I was pretty sure were there—looking under rocks, looking in water, doing all kinds of surveys.”

Caren Goldberg sees eDNA as a way to get answers more efficiently, safely and with less destruction compared to traditional survey techniques. Until recently, scientists depended on netting or using an electric current to temporarily catch fish.

This newer way is becoming popular around the world. Animal experts in Vietnam are using the eDNA to find the last, wild Yangtze giant softshell turtles. On the Caribbean island of Trinidad, it is being used to find endangered golden treefrogs.

Scientists working with it say they do not expect robots to replace field biologists anytime soon. But the old-fashioned field work could soon be more targeted. A related research goal is to show how long environmental DNA can last and how far it can travel in different environments.

32 DNA testing is widely used mainly because ________.

A. its cost has reduced greatly

B. its result is more accurate

C. its procedure is easy to run

D. it frees biologists of hard work

33. What is Caren Goldberg’s opinion on eDNA?

A. It’s hard to put it in actual use.

B. It's helpful only in a limited way.

C. It takes more time to get the results.

D. It may cause less damage to species.

34. What does the underlined sentence mean in the last paragraph?

A. The old-fashioned field work would be more popular.