In accordance with GB 3100~3102—1993 Quantities and Units, units of measurement should adopt symbols, and the name of the units should not be mixed with the symbol of the units. Manuscripts are required strongly to apply legal units of measurement, standard international symbols and correct lowercases and capitals, for example, 50 mg/(kg•d) or 50 mg· kg^-1·d^-1. Unit symbols must be in italic letters (pH is excepted), while the symbols of vector and tensor should be in black italics. When infrequently-used legal units of measurement appeared in the text for the first time, the conversion coefficient with the old unit of measurement should be marked in the bracket, and then the legal unit of measurement can be directly listed in the following text. The unit mmHg or cmH₂O can be used to term pressure in human or animal body, but bracket (1 mmHg=0.133 kPa) should be added when appeared in the text for the first time.