请问lack of representativeness of convenience sampling.

Lack anything,lack of lack of Be lack of 和 lack 高中英语lack和lack of lack of,lacking of 请问short of 和 lack of 有什么区别? 请问short of 与a lack of 怎么区分 lack是a lack of还是lack of 可数么? we never lack of Never lack of man lack of scale? lack of order 是什么意思