单选题
A. activates B. alone C. cases D. certain E. correlations F. damaged G. dominance H. effects I. exclusive J. in K. on L. over M. processes N. together O. wondered If you write with your fight hand, you might prefer to draw a picture, throw a ball or eat food with the same hand. But have you ever 42 if your fight foot is also more active than your left foot? What about your right eye and ear—do you prefer to use them more than your left ones? Each person's brain is divided into two sides—the left and fight hemispheres. In some 43 , one hemisphere may be more involved than the other during a (an) 44 activity. For example, when someone 45 language, one hemisphere is often more active than the other. Doing this or other activities, however, is not absolutely limited to using one hemisphere or the other, or even several hemispheric parts. Different brain areas are important and work 46 for different activities, such as speech, hearing and sight. But if part of a hemisphere is 47 when a person is young, other parts of the brain can often take 48 doing whatever those regions of the brain used to do. What do the brain's hemispheres have to do with sidedness? When someone is saying something, one hemisphere is usually working harder than the other. There are also some 49 between the side (s) we use in our brain and the side we use 50 our body. This preference to use one side of the body over the other is known as sidedness, laterality or left/fight 51 .