contemporary: is likely to apply to people and what relates to them: Abraham Lincoln was ~ with Charles Darwin.


contemporaneous: applies to events: Victoria's reign was ~ with British hegemony.    前两个词来自同一个词根TEMPOR表示time时间，如temporary暂时extemporaneous即席临时temporize拖延时间等待时机


coeval: implies extemporaneousness at some remote time or for a long period and refers usually to periods, ages, eras, or eons: the rise of the leisure class was ~ with the flowering of the arts.    eon纪，如the ambrian eon寒武纪    如the industry is coeval with the construction of the first railways这一产业和初期铁路的建造相伴而生


synchronous: implies exact correspondence between or during usually brief periods of time, and especially in periodic intervals: the ~ action of a bird's wings in flight.   (相应correspond不一定相同，可以有时间差，但"时间差一定恒定"，如本例鸟的不同翅膀)   periodic周期性的，注意periodical不是形容词是名词: 期刊


simultaneous: implies exact coincidence at a point of time: a ~ ringing of church bells miles apart.    如simultaneous attacks/translation/interpreting同时攻击/同声传译


coincident: is applied to events that happen at the same time and may be used in order to avoid implication of causal relationship: the end of World War II was ~ with a great vintage year.      vintage year好酒酿成的年分，有卓越成就的一年            又如coincident birth times出生时间恰巧相同


contemporary同时: 用于人，contemporaneous同时: 用于事件，coeval同时: 用于发生在久远过去，synchronous同步: 指周期性地相应发生，simultaneous同时: 指确切同时发生，coincident凑巧巧合: 强调同时发生的事情之间没有因果关系


记忆方法: 1）首字母CCCSSC，4C想成时钟Clock，2S想成相等Same，两两相等<==同时

         2）同时的意思是同时存在发生mean existing or occurring at the same time.