1 . You don’t have to use a dandelion (蒲公英) to know which way the wind blows. But it can help. Dandelion seeds fly freely in the wind. But those seeds on any given dandelion have different fates. Some are to float north when the wind blows them, while others are fated to fly east, south, west or some direction in between. “How do dandelion seeds respond to the wind depends on where they sit on the dandelion head?” says Jena Shields, a biophysicist at Cornell University in Ithaca.

One day, Jena happened to watch her little child play with dandelions. She noticed that the dandelion seeds didn’t all fall off the same. Some came loose more easily than others, but it depended on how the child blew on the seed heads. Jena got the inspiration for the research from it. So Jena set out to study what was going on.

She measured the force it takes to blow dandelion seeds away. To start with, she glued (粘贴) a wire to the different seeds. Then she pulled them at various angles. This seed-by-seed study mimicked what happens when the wind pushes them over.

The findings show that each seed falls off most easily in the wind from one direction, and seeds from one head don’t go the same way. The feathery seeds on the side facing the wind will fall off most easily. The others hold on more tightly until the wind shifts. Besides, once blown off a dandelion, a seed’s umbrella-like feather carries it on the wind that pulled it away. And it helps explain why the plants are so successful in spreading.

However, Jena also found an exception. A sudden strong blow was still able to blow all the seeds away in the same direction. So when a strong wind blows or excited children try their best to blow, all the seeds could be blown off at once.

1. Why did Jena do research on dandelion seeds?

A．To correct people’s misconception of dandelions.

B．To figure out how dandelion seeds react to wind.

C．To explain why dandelions fly far without wind.

D．To satisfy her child’s curiosity about dandelions.

2. What does the underlined word “mimicked” in paragraph 3 mean?

A．Predicted.

B．Proved.

C．Explored.

D．Copied.

3. What did Jena Shields’ research prove about dandelion seeds?

A．They fly for the similar distance.

B．They tend to fly in one direction.

C．They come off easier in the wind from one direction.

D．They break free from feathers to fly once coming off.

4. What is the purpose of the last paragraph?

A．To make up for the research.

B．To stress the point of the text.

C．To make a summary of the text.

D．To provide examples for the research.