With forcefree model, it is shown that the photospheric transverse current is independent of the sense of the transverse field and can be found completely by vector magnetographic measurement.
并证明了光球横向电流与横向磁场的指向无关，因而完全可以由向量磁象仪测定。
2
Protracting object's free-body diagram is a course of analysising object's force from other object.
画受力图是解决力学问题关键的一步。
3
Mr Krauze remembers that the North American Free-Trade Agreement (NAFTA) came into force in 1994.