than ourselves.

4. What do we learn about existing medical knowledge and skills in the world?

A. They are enough. B. They have not been updated.

C. They are not equally shared. D. They have benefited most of the blind.

5.. ORBIS aims to help the blind by ________.

A. teaching medical students B. training doctors and nurses

C. running flying hospitals globally D. setting up non-profit organizations

6. What does the author try to do in the last paragraph?

A. Appeal for donations. B. Make an advertisement.

C. Promote training programs. D. Show sympathy for the blind.

C

Bedazzling (眼花缭乱) with their bright colors and eye-catching displays, fireworks light up our night skies during the holidays. However, these crowd-pleasers can have some damaging side effects.

Once a firework is set off, it only takes a couple of seconds before smoke, dust and harmful chemicals are let out into the atmosphere. The loud booming noises are caused by gunpowder. While the sounds may excite some people, they can be frightening to domestic and wild animals-as well as some humans.

The pretty colors you see are a result of more chemicals. Barium, added to make green, is known for its poisonous and radioactive qualities. Blue comes from copper compounds. Cadmium, lithium and lead-all found in fireworks-have been linked to diseases, such as allergies and skin rashes in both humans and animals. Acid rain has been linked to gases given off by fireworks, which sometimes go beyond the toxin(毒素) limits of the United States Clean Air Act.

Once all those chemicals come back down to the ground, they can cause problems too. Debris (碎片) from the fireworks falls to the ground, where animals can burn their paws or noses on piping hot pieces. Humans also are at risk of stepping on or picking up something sharp or hot. Meanwhile, debris that finds its way into waterways can damage animal habitats and water supply sources. Instead of setting off fireworks, try to come up with some new ways for fun. Here are some ideas to get you started:

• Sky lanterns-a tradition that originated long ago in the most-populated Asian country.