下列各句均有一处错误，请找出并改正。
1. Help yourself to some chicken, children.
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2. He is very young,and he knows a lot.
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3. His mother teach him at home when he was young.
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4. Because he is too young,so he can't lift the box.
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5. The children enjoyed them in the park.
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小医生，下列各句均有一处错误，请找出并改正。