请问lack of representativeness of convenience sampling.

请问lack of representativeness of convenience sampling. Lack anything,lack of lack of lack of lack of lack的用法请问a lack of、be lacking in和lack for用法上有什么区别? lack of 和lack for 的区别? lack 和lack of 有什么区别? 什么时候用lack ,什么时候用lack of lack 和lack of可以混用? lack of 中的lack是什么词? Lack Of Communication 歌词 Never lack of man lack of order 是什么意思 we never lack of what do you think the boy ___?a.lacks of b.is lacking in c.for lack of d.lack请问应该选哪个?A选项的话lack of 中的lack 不是应该做名词用么？ 请问Lack of education is an obstacle of success.的句子成分?1.　lack 是作名词吗?2.　哪些情况下动词可以直接放在句首? lack of和a lack of的区别?