But how precisely these inputs are converted into a test score is a mystery, and without knowing which lever to pull, it is difficult to design an effective incentive scheme.

但是这些投入究竟是如何精确地转化为测试成绩却是一个谜。如果不知道需要去撬起哪个杠杆，那么是很难设计出一个有效的激励计划的。

youdao

Ignoring can be hard to pull off, but it can be extremely effective.

忽视是很难做到的，但是这却非常的有效。

youdao

A stable, reliable push-pull pulsed wire feeder and its working Principle are introduced. Effective factors of wire-feed stability is also analyzed in this paper.

本文介绍了一种送丝性能稳定、可靠的推拉脉动送丝机及其工作原理，分析了送丝稳定性的影响因素。

youdao

And we know as we go across a row in the periodic table, what's happening is that z effective or the effective pull on the nucleus is increasing.

而我们知道沿着周期表的某一行向右看，有效核电量,或者说原子核的有效引力是在逐渐增大的。

麻省理工公开课 - 化学原理课程节选