og13中control用法求教，谢谢！！！

lsshi8947

In a review of 2000 studies of human behavior that date back to the 1940's, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could me taken seriously.

E psychologists declared that since most of the studies had failed to control for variables such as social class and family size,

请教答案e中，control for是什么用法？ 我查字典control没有不及物动词的用法，为什么这里可以跟for？感谢各位nn！
跟朋友讨论，变量（ 如social class and family size）是不能被控制的，所以使用control不对；变量只能是在study中被考虑，因此推测题目想通过control for表达consider的意思，但查字典control没有不及物动词的用法，即不能跟for，我在这点上就想不通了，请教大家，谢谢！

lsshi8947

没人看吗？

lsshi8947

upupupup~~~~~~~~~~