Through the processes of devoicing and weakening, these initials evolve respectively in the places and the ways of pronunciation in terms of the tones, initials and finals.

The application of chemical cleaning in high pressure air cooling equipment of domestic hydrocracking unit;

Disposal methods of chemical cleaning wastewater on locale;

Study of chemical cleaning formula for circulating water;

The article introduces the post-disposal technology of chemical washing and also discusses the fulling and passivation processes.

Review of Progress in Investment Casting Technology at Abroad Part Ⅸ:High Hydraulic Pressure Cleaning Sand and Chemical Cleaning Sand;