3 . Some of the greatest problems we face today are concerned with the gradual destruction (破坏) of our environment through overuse of our _________. So my family do what we can. We take cloth bags to stores instead of using plastic bags. We walk where we don’t have to _________.

But when I’m the only one with a cloth bag in line at the grocery store, I ask myself: Does it do any good?

I recently found the answer from flamingos (火烈鸟). These beautiful birds gather in _________ groups of a thousand or more. Every year, when the time comes for migration (迁徙), a few flamingos start the process by _________ from the lake. But _________ of the others seem to notice, so the tiny group returns.

However, the next day they _________ again. This time a few more struggle along with them, but the vast majority _________ no attention, so these pioneers come back.

The trend continues for several more days. Every time a few more birds join in but, _________ the thousands of others still take no notice, the great migration plan is once again _________.

Then one day, things __________. The same small group of birds takes wing and a tiny number more join in, just as before. This time their total number is enough to tip the balance (扭转局势). As one, the whole group takes flight and the migration __________.

A few can make a __________. It’s true that all of the great problems of the world have been solved because of the __________ efforts of a few.

If you believe in a cause (事业), don’t __________. Others will someday notice and __________ we will solve even our greatest problems.

5 . A new study has found that ride-sharing services result in much more pollution than other kinds of private and public transportation. Ride-sharing trips also draw passengers away from more environment friendly methods of travel, like public transportation, walking or biking, the study found.

Several studies in recent years have suggested that ride-sharing services like Uber and Lyft can worsen traffic problems in cities. The new study represents an attempt to center on how ride-sharing services affect pollution. Overall, the researchers reported that ride-sharing trips now "result in a 69 percent more climate pollution on average than the trips they replace." The study notes that the same passengers could have chosen to travel by bus, train, bike or on foot.

One of the big reasons they give for this result is that ride-sharing vehicles are often driven with no passengers in the car. This happens when drivers are either waiting for rider requests or on the way to pick up passengers. This situation, known as "deadheading", takes up about 42 percent of all ride-sharing driving activity, the study found. The researchers said that deadheading results in about 50 percent more carbon dioxide than one person driving in a private vehicle. Both Uber and Lyft have said in the past that most studies on the subject overstate (夸大)the effects of their services on pollution. Uber told Reuters news agency in a statement it had no comment on the latest report and that the study made misleading claims about ride-sharing. Meanwhile, the company said it would work directly with cities to address climate changes, promoting sharing trips and other means of transportation.

6 . Earth Hour is organized by the World Wide Fund for Nature. It's a big event usually at the end of March every year. On this evening, people “go dark”.     1    

It's true that turning off lights for just one hour saves only a small amount of power.    2    On one level, joining in Earth Hour makes people think about the problem of climate change and what we can do in everyday life to protect nature.

But on another level, a large number of people’s acting together sends a powerful message to governments and companies.     3     They begin considering green issues when big decisions.

The logo(标识) of Earth Hour is “60+” .The number 60 is for the 60 minutes of Earth Hour.     4     In fact, people who join in Earth Hour say that taking part makes them want to do more for the environment.

    5     Musicians give concerts by playing acoustic(原声的) instruments instead of electric ones, and using candles instead of electric lights. Celebrity chefs have created special recipes for families to prepare and eat by candlelight. Tree-planting sessions, group walks and runs are also among the options.

7 . Help Hermit Crabs

Hermit crabs are nature’s recyclers. They eat waste and help keep oceans and shores clean. Unlike other crabs, the hermit crab has a thin outer shell over its soft tail. This makes the hermit crab easy prey for hungry predators. Hermit crabs stay safe by living in old seashells. A hermit crab is picky; it tries on many shells until it finds one that fits just right. In recent years, however, many hermit crabs have had trouble finding their perfect homes. What is the problems There are not enough shells to go around!

One reason for the seashell shortage is that ocean water is not as clean as it once was. This has caused chemical changes to sea water. Some sea animals, like snails, are affected by these changes. Now there are fewer snails making shells. People visiting the beach often take shells home as souvenirs. This is another problem. Other people even take shells for their own pet hermit crabs! They do not realize that hermit crabs in the wild need those shells too.

Now people are working to solve this hermit crab housing shortage. They are teaching beach-Boers to leave seashells where they belong — at the seashore! Some people even make fake seashells that they hope the hermit crabs will like. For example, a group called Project Shelter invited people who visited their website to create different designs for hermit crab shells.

These designers had a lot to consider. What kind of material should be used to build a seashells. The material must be light enough for the hermit crab to carry, but strong enough to protect the crab from predators. The man-made shells could not contain glue or any other substance that might harm a hermit crab. Another challenge with building a hermit crab home was the opening to the shell. Too big would mean the crab would not feel safe. Too small would be uncomfortable, and the crab would not want to move in.

The Project Shelter shells are placed in the wild for hermit crabs to find. Lucky hermit crabs can move into these new dream homes.