A new study found that nearly half of bald eagles【小题1】(test) across the United States show signs of repeated lead (铅) exposure. Researchers examined the blood, bones, feathers and liver tissue (肝脏组织) of l,210 eagles between 2010 and 20l8.

Lead is a poisonous substance 【小题2】 affects the nervous system and interferes (妨碍) with the normal function of nerve cells. Even in low amounts, lead can reduce bald eagles’ ability 【小题3】 (fly), hunt and reproduce. In high amounts, lead causes 【小题4】(breathe) difficulty and death.

Bald eagles are one of America’s most celebrated conservation success stories. The birds   【小题5】(remove) from the U. S. Endangered Species List in 2007. But scientists say that high lead levels are still 【小题6】 concern. Lead exposure also reduces their ability to face future difficulties, such as climate change or infectious diseases.

“Lead is available to these birds more than we 【小题7】( previous) thought,” said VinceSlabe, a research wildlife biologist at the nonprofit group Conservation Science Global.

The blood samples from live eagles in the new study were taken from birds trapped andstudied 【小题8】other reasons. The bone, feather and liver samples came from eagles killed by vehicles, power lines or other causes.

The researchers also found higher levels of lead exposure in fall 【小题9】winter. During these months, eagles eat animal remains left by hunters. These remains often contain many【小题10】(piece) of lead ammunition (弹药).

Three million years may seem like a long time. But when you consider that planet Earth is more than 4.5 billion years old, it is a pretty short period of time.

The blue whale, 【小题1】 (weigh) more than even the biggest dinosaurs, is the largest animal that has ever lived. They can grow 【小题2】 30 meters long and be as heavy as 130,000 kilograms. 【小题3】 for millions of years, they were not nearly that large, scientists say. “All of a sudden — ‘boom’— we see them get very big, ” scientist Nick Pyenson said. He and other 【小题4】 (researcher) recently published an article on whale size. “It’s like going from whales 【小题5】 size of minivans (面包车) to longer than two school buses, ” Pyenson added.

The scientists believe that a change in the Earth’s climate caused whales 【小题6】 (get) so large only about 3 million years ago. This change led to food becoming more 【小题7】 (easy) available. An oncoming ice age made the ocean water cold and brought more nutrients, resulting in more food for large whales. Whales 【小题8】 were able to quickly eat a lot of food survived, and got 【小题9】 (large). Over the next three or four million years, the blue whales grew 10 times bigger than they 【小题10】 (be), the scientists say.

Goldfish may look small and cute in your home, but in the wild, it’s a different story. Releasing【小题1】(they) into your local stream or lake isa bad idea. Right now, Washington State 【小题2】(fight) off an invasion (入侵) of goldfish!

Thousands of goldfish are living in the West Medical Lake 【小题3】 they are crowding out the native fish population. How did this happen? The Department of Fish and Wildlife thinks a few irresponsible pet 【小题4】 (own) are to blame. Although the goldfish may have cost the owners a few dollars, this mess is going to cost the state about $150,000 to attempt 【小题5】 (remove) these harmful fish.

What’s more, Goldfish are invading lakes and streams worldwide, and it’s all our fault.

If you think you’re doing the goldfish 【小题6】 favor by releasing it, you’re wrong! Instead, you’re setting the stage for a(n)【小题7】 (ecology) disaster, which could threaten hundreds of other species. It turns out that goldfish are one of the world’s 【小题8】(bad) invasive species. They introduce diseases that destroy the 【小题9】 (delicate) balanced ecosystems wherever they go. And they aren’t happy to stay in one place and will travel across many bodies of water.

So think twice before 【小题10】 (throw) that goldfish away.