A longitudinal approach is conducted to investigate the development of productive vocabulary which L2 students have manifested on the three indices of oral production.

For this reason,multiple electric means have been used during advanced investigation:in which,use the symmetric profiling and IP sounding to define exact location of coal seam outcrops;five-electrode longitudinal axis sounding and IP sounding to define coal seam buried depth and thickness;high density electric surveying to define coal seam strike extending.