When it comes to car hiring,all car hire companies require that you should have a full driving license for at least one year,some of whom may ask for two years,especially for younger drivers.

    Most car hire companies will not automatically hire out a car to someone under the age of 25 or to people over 70. But there are exceptions. Some listed companies are normally prepared to serve people of 21 and over. And some may go over the age limit and provide service for older people( aged 70 and over) providing you have no record of breaking the law and valid license, and a doctor's letter of good health.

    Now read on for some information about national companies with many bases hiring out cars to people aged 21 and older drivers.

“缥缈的雾，晶莹的露，凝重的霜，轻柔的雪，同样的水分子，装扮着我们生活的时空”．这是一首描述物理现象的抒情诗．对这首诗中所描述的物理现象理解正确的是（　　）