billion的意思是亿还是十亿?

Today there are 6.4 billion people on the earth. By the year 2050 there may be 12.5 billion . There are a lot of people to feed. We need more and more food.
One way to produce more food is growing stronger plants. For thousands of years, farmers have made plants better. Every season, they pick the best plants for the next season. It works very slowly. Since 1983, scientists have been able to change plants more quickly by changing their genetic（遗传的） material. Foods from plants grown in this way are called genetically modified(改变的) foods, or GM foods.
By changing the genetic material of a plant, it is possible to make new plants. They make plants which are strong against plant diseases. They can also help in our diseases; a kind of rice is being prepared , for example , which stops people becoming blind.
Rich countries produce GM foods because they are easy to grow and bring in more money. Poor countries are interested in them because they help produce more food.
GM plants are not natural. No one knows how good or bad they are,. Making GM foods is only one way of feeding people in 2050. There are strong feelings against them, because they are unnatural. They may feed people , then hurt them or their children later. But both rich and poor countries are interested in their use, and they are not going to go away. In 2050, we may think differently about them.
小题1:GM foods are made by
A. farmers B. workers C. scientists D plants
小题2:What are the good things about GM foods ?
A. They make plants strong against diseases. B. They are unnatural.
C. They can help in human diseases. D Both A and C.
小题3:GM foods .
A. are a quick way to produce food B. grow in the wild
C. are safe D are grown only in rich countries
小题4:Why do some people not like GM foods?
A. They are not useful. B. They are not helpful.
C. They are not natural. D They are not cheap.
小题5:From the passage we know that .

A．GM foods will disappear one day in the future

B．GM foods will not disappear in the future

C．People will not be interested in GM foods.

D．People will have to stop using GM foods

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The $11 billion self-help industry is built on the idea that you should turn negative thoughts like “I never do anything right” into positive ones like “I can succeed.” But was positive thinking advocate Norman Vincent Peale right? Is there power in positive thinking?
　　Researchers in Canada just published a study in the journal Psychological Science that says trying to get people to think more positively can actually have the opposite effect: it can simply highlight how unhappy they are.
　　The study’s authors, Joanne Wood and John Lee of the University of Waterloo and Elaine Perunovic of the University of New Brunswick, begin by citing older research showing that when people get feedback which they believe is very positive, they actually feel worse, not better. If you tell your stupid friend that he has the potential of an Einstein, you’re just underlining his faults. In one 1990s experiment, a team including psychologist Joel Cooper of Princeton asked participants to write essays opposing funding for the disabled. When the essayists were later praised for their sympathy, they felt even worse about what they had written.
　　In this experiment, Wood, Lee and Perunovic measured 68 students’ self-esteem. The participants were then asked to write down their thoughts and feelings for four minutes. Every 15 seconds, one group of students heard a bell. When it rang, they were supposed to tell themselves, “I am lovable.”
　　Those with low self-esteem didn’t feel better after the forced self-affirmation. In fact, their moods turned significantly darker than those of members of the control group, who weren’t urged to think positive thoughts.
　　The paper provides support for newer forms of psychotherapy (心理治疗) that urge people to accept their negative thoughts and feelings rather than fight them. In the fighting, we not only often fail but can make things worse. Meditation techniques, in contrast, can teach people to put their shortcomings into a larger, more realistic perspective. Call it the power of negative thinking.
小题1:What do we learn from the first paragraph about the self-help industry?

A．It has produced positive results.

B．It is a highly profitable industry.

C．It is based on the concept of positive thinking.

D．It was established by Norman Vincent Peale.

小题2:What does the word “underline” mean (Line 4, Para. 3)?

A．point out

B．lay emphasis on

C．pay no attention to

D．take for granted

小题3: Which of the following is TRUE about the Canadian researchers’ study?

A．Encouraging positive thinking many do more good than harm.

B．Self-affirmation can bring a positive change to one’s mood.

C．There can be no simple therapy for psychological problems.

D．Forcing a person to think positive thoughts may lower their self-esteem.

小题4:What do we learn from the last paragraph?

A．Meditation may prove to be a good form of psychotherapy.

B．People can avoid making mistakes through meditation.

C．Different people tend to have different ways of thinking.

D．The effects of positive thinking vary from person to person.