题目内容：

    This morning we're going to head off down into the wetland, into a very specific kind of wetland called the Prairie fen.

You can find Nate Fuller counting butterflies. The Sarett Nature Center needs an accurate count of Mitchell's satyr butterflies to help preserve one of their last known habitats. They're very particular about the kind of habitat where they can live, which is part of what makes them so rare and amazing indicators for our water quality. Today, Sarett expert Ashley Cole-Wick with Michigan's Natural Features Inventory helps Fuller count. She says "When I first started working on the butterfly in 2013, we had 18 populations and this year in 2019, we have 10."

The Mitchell Seder went on the endangered species list in 1991. Initially it was thought that loss of wetlands contributed to their decline. Fuller says "It's not just habitat availability. Its groundwater and the amount in the quality of groundwater coming into these wetlands seem to be a challenge for the butterfly. Nothing has all been sorted out exactly. ” While the decline is likely a combination of factors. the fact that water quality might contribute is alarming because the wetlands are the headwaters for the Midwest's rivers and streams.

A captive breeding （人工繁殖）program was started four years ago at the Toledo Zoo to help get to the bottom of the mystery. Today Director Ryan Walsh who heads the program says it's been, the only successful captive program. The caterpillars （毛毛虫）spend the winter in a special weather control room that help determine the Mitchell satyrs don't do well below 4. 4 degrees Celsius, a temperature that prevents the Fen wetlands from the hard freezes which kill the insects. With that knowledge, the program produced 1300 new eggs this summer, a development that may go a long way toward restoring the population. And if all goes well, may one day the Mitchell satyr butterfly earn a ticket off Endangered Species List.

1.What are the indicators for the water quality?

A.The habitats. B.The butterflies.

C.The wetlands. D.The experts.

2.What is the main idea of the third paragraph?

A.The importance of water quality.

B.Actions taken to protect the butterflies.

C.The reasons why the butterflies decline.

D.The natural conditions for the butterflies.

3.What does the underlined word "restoring" in Paragraph 4 most probably mean?

A.Preserving. B.Increasing.

C.Recovering. D.Controlling.

4.What can we learn about the butterfly?

A.It can easily be found. B.It is not endangered now.

C.It will die above 4. 4 degree Celsius. D.It can be bred by humans.