e.g. i.e. etc. et al. w.r.t. i.i.d.
用法：, e.g., || , i.e., || , etc. || et al., || w.r.t. || i.i.d.
e.g. 拉丁文exempli gratia的缩写，意思是“举个例子，比如，例如…..”。Popular pets, e.g. , cats and dogs.
i.e. 源于拉丁语id est的缩写，意思是“那就是说，换句话说”，等同于“that is, in other words, namely”。The basic essentials of life, i.e. , housing, food and water.
etc. et cetera的缩写，意思是“等等”，相当于“and so on”，用于列举事物。We talked about the contract, pay, etc.
et al. 源于拉丁语et alibi的缩写，意思是“等等”，相当于“and others”，用于列举人。Research by West et al., 1996.
w.r.t. with repect to缩写，“关于”；“谈及”；“谈到”。Their PDFs are differentiable almost everywhere w.r.t. both sigma and z.
i.i.d. independent and identically distributed 缩写 "独立同分布"。Dataset X={x_i, i = 1...N} consisting of N i.i.d. samples of some continuous or discrete variable x.