阅读短文，用方框内所给单词的适当形式填空。
| succeed, they, work, careful, make, so, happy, close, one, few, either, but |
Do you use your right hands more or left hands more? Very 1______ of us use both of our hands well.
Most people use right hands. Only about five people of a hundred use left hands. New-born babies can take
things with 2______ of their hands, 3______ in about two years, they like to use 4______ right hands.
Scientists don't know why this happens. They've studied it. They think our animal ancestors used their
right hands, this may not be true. Monkeys are our 5______ relatives in the animal world. Scientists have
found that monkeys like to use one of their hands more than the other----but it can be either hand. There are
as many right-handed monkeys as the left -handed 6______. Next time you visit the zoo and do watch the
monkeys 7______. You'll see that some of them will use their right hands and others will use their left hands.
But men use their right hands better and this 8______ life difficult for the left-handed ones. We live in a
right-handed world. Some scientists have found out that more of 9______ people are left-handed, but they
don't know why. But they are 10______ hard to discover the secret.