Uh­oh, the new year's just begun and already you're finding it hard to keep those resolutions to junk the junk food，get off the couch or kick smoking. There's a biological reason why a lot of our bad habits are so hard to break—they get deep­rooted in our brains.

That's not an excuse to give up. Understanding how unhealthy behaviors become deep­rooted has scientists learning some tricks that may help good habits replace the bad.“Why are bad habits stronger? You're fighting against the power of an immediate reward. We all as creatures give greater value to an immediate reward than something that's delayed，” says Dr Nora Volkow, director of the National Institute on Drug Abuse.

Just how that bit of happiness turns into a habit involves a pleasure­sensing chemical named dopamine(多巴胺). It trains the brain to want that reward again and again—increasing the connection each time—especially when it gets the right cue(暗示) from your environment.

People tend to overestimate their ability to resist temptations around them, thus destroying attempts to get rid of bad habits. Even scientists who recognize it find it hard to resist.“I don't like popcorn. But every time I go to the cinema, I have to eat it，” Volkow says.“It's fascinating.”

A movement to pay people for behavior changes may make use of that connection, as some companies offer employees immediate payments for adopting better habits. However paying for behavior turns out, researchers say there are some steps that may help counter your brain's hold on bad habits: repeat，repeat，repeat the new behavior—the same routine at the same time of day. Determined to exercise？Doing it at the same time of the morning makes the brain recognize the habit eventually. If you don't do it, you feel awful. Exercise itself raises dopamine levels, so eventually your brain will get a feel­good hit even if your muscles protest. Reward yourself with something you really desire, Volkow stresses. You exercised all week? Stuck to your diet? Buy a book, a great pair of jeans, or try a fancy restaurant.

20．What's the subjective reason for being hard to break bad behaviors?

A．Some behaviors get deep­rooted in our brains.

B．We prefer an immediate reward.

C．We value delayed gifts.

D．We are all creatures of nature.

21．What does the underlined word “connection” in Paragraph 3 refer to?

A．Pleasure and behavior.  　B．Brain and reward.

C．Happiness and dopamine.  　D．Cue and environment.

22．It can be inferred that the higher the dopamine level is，________．

A．the harder it is for you to break the bad habit

B．the less pleasure you will get

C．the stronger bad habits will become

D．the more you'll want to get a reward

23．Why does Volkow eat popcorn even though he doesn't like it?

A．Because he recognizes the importance of him.

B．Because it is needed for normal growth of the body.

C．Because he can't resist the temptation of it.

D．Because it makes him relaxed to eat popcorn while seeing films.

Energy is very important in modern life. People use energy to run machines, heat and cool their homes, cook, give light, and transport people and products from place to place. Most energy comes from fossil fuels—petroleum, coal, and natural gas. However, burning fuels causes pollution. Also, if we don’t find new kinds of energy, we will use up all the fossil fuels in the twenty-first century. Scientists are working hard to find other kinds of energy for the future. What might these sources of energy be?
Energy from the wind
All over the world, people use the power of the wind. It turns windmills and moves sailboats. It is a clean source of energy, and there is lots of it. Unfortunately, if the wind does not blow, there is no wind energy.
Energy from water
When water moves from a high place to a lower place, it makes energy. This energy is used to create electricity. In Brittany, France, for example, waterpower produces enough energy to light a town of 40,000people. Waterpower gives energy without pollution. However, people have to build dams to use this energy. Dams cost a lot of money, so water energy is expensive.
Energy from the earth
There is heat in rocks under the earth. Scientists use this heat to make geothermal energy. San Francisco gets half of the energy it needs from geothermal power. This kind of energy is cheap, but it is possible only in a few places in the world.
Energy from the sun
Solar panels on the roofs of houses can turn energy from the sun into electricity. These panels can create enough energy to heat an entire house. Solar power is clean and there is a lot of it in sunny places. But when the weather is bad, there is no sunlight for energy.

1. 1.

   What does this passage mainly talk about?

   1. A.
      Advantage of the energy from nature.
   2. B.
      The future of the energy.
   3. C.
      Scientists have been working hard to research other kinds of energy.
   4. D.
      Energy is the most important power in the word.
2. 2.

   From the first paragraph we know ______.

   1. A.
      energy can do everything for people
   2. B.
      all the energy causes pollution
   3. C.
      the new kinds of energy are badly needed
   4. D.
      scientists have found other kinds of energy for the future
3. 3.

   What is the writer’s opinion about the energy?

   1. A.
      Try to use water energy more though it costs a lot.
   2. B.
      Each natural energy has its own advantages and disadvantages.
   3. C.
      Solar power is environmental.
   4. D.
      Wind power is the cheapest but we can’t get.
4. 4.

   What can be inferred from the passage?

   1. A.
      In order to protect our environment, we should try other kinds of energy.
   2. B.
      All scientists in the world will unite to find energy.
   3. C.
      People in modern life use energy every day.
   4. D.
      Energy changes people’s lives.