Scientists and others in the psychological, sociological fields have asserted that humans use maybe 0.01 to 0.10 percent of our brain. Here is an easier way of understanding what that means.First let us make it clear that mechanically you use 100 percent of your brain. Enhancing usage to its maximum is another subject. So when someone puts a percentage of use on the brain they do not mean that the other, say 90 percent, is not active or useless.Think of it this way. Let’s say your brain is a stereo (立体声音响). When you are using your stereo you are using 100 percent of it. If the volume knob (旋钮) is set at a 2 level, then you are not getting the same usage when compared to turning the volume knob to 8 or 10.So what scientists are trying to get across to us is we have a lot more room in our cranium (头盖骨) to fill. We have more volume to boost. We are not even close to tapping our potential of brain power.There is no physical data to determine in clear evidence the amount of usage the human brain has. However, there has been data that has shown that people have increased their brain power. Then there are the people who show mental abilities that are very rare. Some people with autism (自闭症), for example, have had the ability to calculate very high levels of math equations (方程式) without ever having learned how.There are also more and more variables we are learning about the brain. Studies suggest that even though our brain is one as a whole, we evidently get production out of separate parts of the brain for different mental tasks. We have all heard of the right brain/left brain references for example.So regardless of how you want to interpret the brain usage by percentage, the fact is that it is the most amazing gift we have. A computer is nothing compared to the human brain. And we can build upon our ability to get more out of it. So turn up the volume button and get the brain working.1. What is the problem mainly talked about in this passage?A) More than 90 percent of our brain is not active.B) More than 90 percent of our brain is not suitable for use.C) More than 90 percent of our brain is not used to the maximum. D) More than 90 percent of our brain use is not known to scientists.2. In Paragraph 3, the author’s main purpose is to _________.A) give us instructions about how to better use a stereoB) show the difference between volume levels in a stereoC) make us understand why we are not fully using our brains D) determine how loud music affects the functions of our brains3. What do the scientists mean by “we have a lot more room in our cranium to fill” in Paragraph 4?A) There is still some space for the brain to grow.B) There is still some potential in human brains to explore. C) We still have a long way to go in the study of human brains.D) We still have different opinions about the proper use of our brain.4. What does the author try to show with the example of people with autism?A) The brain has an unlimited amount of usage.B) Some people may have special mental abilities. C) The brain has different parts to perform different tasks.D) Some people may increase their brain power through learning.5. What does the author encourage the reader to do in the last paragraph?A) Listen to more music.B) Learn more about our brains.C) Improve our computer skills.D) Make more use of our brains.