题目内容：

Northern California’s national parks appear pure and clean, almost untouched. But scientists are finding that there is more to this wild area than one can see. Even in the deep forests and on the mountain tops, animals may be poisoned by pesticides (杀虫剂) used in valley farms far below.

Researchers with the United States Geological Survey  (美国地质勘探局) are working late into the night. They are searching for and catching frogs in the mountains of the Sierra Nevada. The Pacific chorus frog (拟蝗蛙) breeds in the high mountains just as the snow melts. The pools basically fill with meltwater, and as soon as the ponds melt the chorus frogs begin breeding there. Some Pacific chorus frogs in the mountains of California have tested positive for farming pesticides.

Gary Fellers is a researcher who once worked for the USGS. He and other team members are collecting the frogs to test them for agricultural poisons. No one farms in these forested national parks. However, winds carry chemicals from the Central Valley farming area into the mountains.

Kelly Smalling was the lead writer of the USGS study. “The decline of amphibians (两栖动物) has been documented for decades and decades. Some populations have gone extinct. And why these populations are declining is still a mystery.” Ms. Smalling says pesticides could be harming frogs and other amphibians.

The researchers tested pond water and soil from the bottom of the ponds.  They were clean or almost free of  pesticides. But tests on the bodies of the frogs showed the presence of 12 agricultural pesticides.

The concentration on the frog becomes greater than the concentration that is present on the water or some other part of the environment. Kelly Smalling says the next step is to find a way to deal with the pollution. “The first thing we need to do is understand how these chemicals that we’re finding harm the frogs. We have to understand the problem before we can fix it.”

1.Animals in Northern California’s national parks ________.

A. are well protected

B. are killed by air pollution

C. are harmed by pesticides

D. will be sent to the farms in the valley

2.According to the text,  the Pacific chorus frogs ________.

A. breed when it snows

B. are only found in the ocean

C. are studied by the scientists

D. are free from the farming pesticides

3.What will the researchers do next?

A. Keep the pond clean.

B. Deal with the pollution.

C. Find new homes for the frogs.

D. Search for and catch the frogs.