①时间单位:采用d、h、min、s而不用天、小时、分钟、秒。②关于分子量、原子量名称和符号。我国法定单位将“原子量”改为“相对原子质量”(符号为Ar),“分子量”改为“相对分子质量”(符号为Mr),不再用Dalton(D,道尔顿)或u,如分子量为64 kD,应改为相对 ① time units: the use of d, h, min, s instead of days, hours, minutes, seconds. ② on the molecular weight, atomic weight names and symbols. In our country, the legal entity changed “atomic mass” to “relative atomic mass” (symbol Ar) and “molecular weight” to “relative molecular mass” (symbol Mr) instead of using Dalton (D , Dalton) or u, such as a molecular weight of 64 kD, should be changed to relative