Secondly, based on the analysis to the characteristicoffield system, the writer put forward the transportation potential to calculation the pause rate of the expressway service area.
其次，在分析场论基础上提出了测算高速公路服务区驶入率的交通势理论。
2
This metallic core gives Earth its characteristic magnetic field, which has played an extremely important role in the history of our planet.
这种金属核赋予地球特有的磁场，在地球的历史上发挥了极其重要的作用。
3
When the turtles were exposed to a magnetic fieldcharacteristicof a coastal area about 209 miles north of their homes, they invariably swam southward.