speedometer

Sometimes the instruments are read-only, like your speedometer. .有些仪器是只读的，就像速度计一样；

Once the speedometer is placed in a conventional sedan, the system test for the sedan would not road test it at 160 miles/hour..但是一旦将速度计安装到家用轿车里面时，对于整部轿车的系统测试将不会在公路上测试160英里/小时这一速度值。

A population study from Finland has developed a fascinating scale that can predict 20-year risk for dementia –sort of a brain aging speedometer..一项芬兰的人口学研究给出了一个引人注目的量表，能够预计20年罹患失忆症的风险，即一种大脑衰老的速度计。