保持孩子健康的最佳方式是让他们保持活跃并均衡饮食。
唯一的限制是你自己设定的限制。
"Books are the keys to unlocking our imagination."
Success is not about the destination, it's about the journey.
The pursuit of mathematical knowledge is a journey that never ends.
解析:天地之所以能长久存在,是因为它们的一切运作都不为自己,所以能够长久。