suffocate: is likely to imply the impossibility of breathing because of the absence of oxygen, the presence of noxious gases, or interference with passage of air to and from the lungs: ~ing under the sand which had fallen upon him.      常作不及物动词，又如many dogs have suffocated in the cars许多狗在汽车里给闷死了


asphyxiate: is likely to refer to situations involving death through lack of oxygen or presence of toxic gas: several people were ~ by calorine escaping from the wrecked train.


stifle: is apppropriately used to refer to situations where breathing is difficult or impossible because of inadequate fresh air: the room's ~ing atmosphere.


smother: is usable in situations in which the supply of oxygen is or seems inadequate for life and often suggests a deandening pall of smoke, dust, or impurities in the air: ~ed by a blanket of volcano ash.       如he smothered the baby with a pillow用枕头把婴儿捂死了


choke: suggests positive interference with breathing, for example by compression, obstruction, or severe inflammation of the throat: ~ on a bit of apple.


strangle: similar to choke, more consistently implies a serious or fatal interference: ~d to death by the assailant.


suffocate窒息: 死于无法呼吸，因缺氧毒气气管堵塞，asphyxiate窒息: 同样表示死于缺氧或毒气，stifle憋闷不透气: 缺少新鲜空气，smother捂死: 用烟尘毯子等覆盖物捂死，choke哽噎: 因喉咙挤压堵塞发炎而阻碍呼吸，strangle勒死: 严重致命地阻碍呼吸


记忆方法： 1) 首字母重新排序为ASS(驴=donkey)和SCS(南海South China Sea)<==驴渡南海时因缺氧窒息    strangle最严重的致命，suffocate，smother和asphyxiate也致命，choke和stifle较轻，仅表示阻碍呼吸或空气不新鲜
                 
                 2) 窒息的意思是阻断呼吸mean to interrupt the normal course of breathing.首字母重新排序为ASS(驴=donkey)和SCS(南海South China Sea)<==驴渡南海时因缺氧窒息