keep是系动词，后面加形容词，如keep healthy
例句：
Keep healthy by eating well and exercising regularly.
通过良好饮食和经常性锻炼保持健康。
Keep healthy by exercising regularly.
经常锻炼以保持健康。
It is very important for us to keep healthy.
我们需要保持健康。
Many people practice it to keep healthy.
许多人练习它以保持健康。
To keep healthy, you should give up the habit of staying up late.
为了保持健康，你应该停止熬夜。
