About 90% of people in the world today arc right-handed. The other 10% arc left-handed, including Obama, the President of the US. Every day, left-handed folks quietly face problems. It could be something as simple as driving a car or using a can opener.
Why are so few of us left-handed？ One theory is that handedness (hand preference) could be a result of genetics. Scientists say that there are two genes（基因）associated with handedness. One is the D gene. It is more frequent in the population and promotes（促成）right-hand preference. The other is the C gene. It has the ability to promote a preference for cither hand．When the C gene is present, there is a 50% chance that a person could be right- or left-handed.
Another theory has to do with human brains, which arc made up of two halves. If the left half is more powerful, then one is most likely right-handed. But with left-handers, it is more complicated．Seventy percent of them are also left-brain dominant（占优势的）. The other 30% have right-side dominant brains.
During the 18th and 19th centuries, left-handedness was considered a disability. But not all of the myths about left-handers are bad. One myth suggests that they are more creative and smarter than the right-handers. So far scientific research has yet to find any truth to these claims. In fact, a 2013 survey out of New Zealand found that left-handers and right-handers were the same.
Life might be a little more complicated for left-handers when it comes to cutting a piece of paper or opening a bottle of wine. However, it seems to be a good sign if you are trying to make it to the White House.
The right-handers arc nine times as many as the left-handers.
A.True
B.False
C.Not Given
Using a can opener could be a problem for left-handers.A.True
B.False
C.Not Given
Men are more likely to be left-handed than women.A.True
B.False
C.Not Given
Left-handers are proved to be cleverer.A.True
B.False
C.Not Given
The New Zealand survey found left-handers differ greatly from right-handers.A.True
B.False
C.Not Given
There are not enough specially-designed tools for left-handers.A.True
B.False
C.Not Given
Some scientists believe that handedness is decided by genes.A.True
B.False
C.Not Given
In the 19th century, left-handedness was no longer considered abnormal.A.True
B.False
C.Not Given
Right-handers live longer than left-handers.A.True
B.False
C.Not Given
Most left-handers are right-brain dominant.A.True
B.False
C.Not Given
题目内容
（请给出正确答案）
如搜索结果不匹配，请 
