题目内容：

Butterflies at Risk

What's causing problems for these beautiful insects?

Something is harming the monarchs. One of the largest butterflies in North America, monarchs are famous for their long migrations（迁徙）covering thousands of miles. Yet the number of monarchs is dropping. Bad weather conditions, putting the butterfly population in danger. Some butterfly experts say that the number of monarch butterflies has been cut by 25 percent. In recent years, unusually cold temperatures and rain have caused monarchs to die in large numbers. These conditions have also caused new butterflies not to hatch（孵化）.

Will they return?

Monarchs are very sensitive（敏感的）to change because of the long distances they travel. They cover thousands of miles each year, flying between their winter homes in Mexico or Southern California and their summer homes in the Midwest. Other animals also migrate. And many travel much farther. A bird called the Arctic tern goes round trip between the Arctic and the Antarctic every year. Like the Arctic tern, a type of gray whale has a long migration. It travels 12,400 miles from Baia California in Mexico to waters off Alaska and back. The longest migration ever recorded is by the sooty shearwater. Every year this bird flies 40, 000 miles from New Zealand to the northern part of the Pacific Ocean to find food.

The monarchs don't travel as far as animals like the Arctic tern and the sooty shearwater, but their journey isn't safe. Every year as many as 100 million monarch butterflies leave Mexico for the first leg of the migration. It's hard to imagine that such a large number might be in danger. Yet many scientists tell us that the danger is very real.

In Mexico people are destroying the natural environment. They cut down the trees where millions of monarchs. spend the winter and use chemicals to kill the milkweed, the monarch's favourite food. Monarchs spend the winter in Mexico and California. In both places, development is destroying these winter homes. Unless steps are taken to protect their habitats, the monarchs' migration could become a thing of the past.

"If we lose the whole migration, we lose one of the nation's most magnificent phenomena, " said Chip Taylor, a professor at the University of Kansas. These butterflies are the symbol of richness of biological diversity（生物多样性）.

1.Are monarch butterflies famous for their long migrations?

2.What are putting the butterfly population in danger?

3.Where are monarchs' winter homes?

4.In Paragraph 2, what animal has the longest migration?

5.What can people do to protect monarch butterflies?