How to keep healthy

    Everyone wants to be healthy,but do you know how to keep healthy? First, eating right food is very important. There is a lot of healthy food. It can make you strong. You can have more bananas,apples,tomatoes,cucumbers and so on, because fruits and vegetable are good for you.But you should not eat too much chocolate or fast food.They're not healthy food.Second,sports can also keep you healthy.Get up early and do some sports every day.You will be healthy and happy by doing so.

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体液中Ca²⁺含量太低时，神经、肌肉的兴奋性升高而出现抽搐,说明Ca²⁺的作用之一（    ）