完形填空,阅读下面的短文，从短文后各题所给的选项中选出能填入空白处的最佳答案。

Bees live in a house that is called a hive. There are three kinds of bees: workers, drones (雄蜂) 1queens. Only one queen bee can live in each hive. If she is lost or dead, the other bees 2 their work.

Workers are very clever and busy. They all join together3 small rooms called cells of wax for their honey. Each worker bee does its own work. Some go out and collect honey from the flowers; 4 stay at home and work inside the hive. The cells5have six sides are made by worker bees. Did you ever look into a glass hive and see them while at work? It is 6to see how busy they always are. Before winter comes, all the drones are driven from the hive7 they don't eat the honey they did not collect.

It is not safe 8 children to be too close to bees. Bees have painful stings they use in their defense (防御).

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The weather is closely related(联系) to our life. It is all around us all the time. It is an important part of our lives. We cannot control it, but it often controls how and 1 we live, what we do, what we wear and what we eat. Read this passage and learn 2 about the weather.

      What is the weather?

The weather is just the state of the atmosphere 3any time, such as temperature, wind, 4 ,sun,etc.

      What makes the weather change?

As we know, not every place on the earth gets the same amount of sunlight. Some places get 5 sunlight, so it's warmer in those places. However, some places get little 6 no sunlight in winter. Then those places have colder temperatures. These differences in temperature make the air and water7 around the earth. The movement helps to take the heat energy from the sun across the earth. So the 8 changes.

     What's the difference between weather and climate?

    Climate is a place's weather over a long time. The weather changes from day to day and  9 from hour to hour. It can be sunny in the morning and cold and wet in the afternoon. But the climate changes very   10over lots of years. 

    April 22 is Earth Day. Everyone on Earth should care about and protect the earth!

The earth has warmed by about 1°F (华氏度) over the past 100 years, but why and how? Well, scientists are not quite sure. Maybe the earth gets warmer and warmer on its own. But many scientists say that people are doing many things which make the earth warmer. First, greenhouse effect (温室效应) is a very important reason for the change of the earth. People give out too much energy into the air every year. It makes the earth warmer. Climate (气候) change is another important reason. Sometimes it becomes too hot and sometimes too cold. Sometimes there is too much rain and sometimes too little. The change of the climate makes the earth warmer. In turn, the warmth of the earth changes the climate, too.

When the earth becomes warmer, there may be more rain and a rise in sea level. It will affect the growth of plants, animals and people. On a Pacific island, 100 people have to move to higher ground because the sea is rising. These people can no longer live on the coast. Before that, two islands without people went underwater in 1999. Scientists say that the seas can rise by nearly one meter by 2100.

People can affect the earth's air, land and water. As for us, we can do many things to protect the earth. For example, we can use fridges less. We can tell more people about protecting the earth.

    Natural resources that we use are things that come from the Earth.

    Our natural resources are limited(有限的）. This means that they will not1 forever. Some are renewable, like when you plant a new tree when you2 one down. Others are not renewable, like when you dig coal(煤）out of the3. Once it is used, it is gone.

    People realize the4 that the Earth's natural resources are limited, and people can do things to help conserve(节约）those resources. 5 you try to conserve a natural resource, you try to use less of it so it does not run out so 6One way that people conserve fuel, like gasoline, is by riding a bicycle or walking when the 7 is short instead of driving everywhere.

    Water is a very important natural resource because we all need it to stay 8. We can conserve water9 making sure that the pipes and taps do not leak(漏）. We can also make10 choices to conserve water, like only using the dishwasher or washing machine when they are full. Everyone can make contribution to protecting natural resources.

    The world of the out-of-doors is full of secrets (秘密). And they are    1interesting that quite a lot of people are busy 2them.

    All around us are birds, animals, trees and flowers. The facts about how they3 and grow are as interesting as anything could be.

    Do you know that one of the great presidents of the USA 4 hours and hours5birds? A businessman who lived near New York became so 6in insects(昆虫) that he began to get 7 together. He now has more than one thousand different kinds of insects carefully 8in glass boxes.

    Come up with me, and I will help you find some nature's secrets. Let us go9 through the woods and fields. Here we shall find how a rabbit tells the others there is danger. We shall 10 a mother bear and her young ones as they look for11and get ready for winter sleep. We shall watch bees(蜜蜂)dancing in the air to let other bees know 12 they can find food.

    I will 13 you many other interesting things, but the best thing that I can14 you is to keep eyes and ears15 when you go out of doors. Nature tells her secrets only to people who look and listen carefully.