If the pupils who received vouchers differ from those who don't—perhaps simply by coming from the sort of go-getting family that elbows its way to the front of every queue—any effect might simply be the result of any number of other factors.
If the pupils who received vouchers differ from those who don't—perhaps simply by coming from the sort of go-getting family that elbows its way to the front of every queue—any effect might simply be the result of any number of other factors.
如果接受补助的学生同没有接受补助的学生之间存在差异——或许仅仅是因为来自那种喜欢插队、事事争先的家庭——任何影响可能就是其他多种因素作用的结果。