There is no systematicdifference in membership between the group of mechanics who do first-time jobs and the group of those who do rework jobs.
在第一次工作的技工组和返工的技工组之间没有系统性差异。
2
The two groups are chosen at random, so the remedy should be the only systematicdifference between them.
这两个组是随机抽取的，所以他们在系统中的唯一区别就在是否接受治疗。
3
A systematic review of 162 scientific papers published in the scientific literature over the last 50 years, however, found there was no significant difference.