接触阻力很难测量。
在基于专家经验的方法中，精度来源于评估人员的知识和经验，很难测量和验证。
In expertise-based methods accuracy is a product of the estimator's expertise and experience, which cannot be easily measured and validated.
这对于那些依赖于流量读数的控制尤其是如此，这些流量读数在低流量速率下是很难测量的。
This is particularly true of controls relying on flow readings that are difficult to measure at low flow rates4.
交调失真的不对称性描述了功率放大器的记忆特性，但是与幅度相比，交调分量的相位特性很难测量。
Asymmetries of intermodulation distortions describe the memory effect of power amplifiers (PAs), but it is hard to measure asymmetries of the phase of the IM components.
火电厂和冶炼工厂附近的土和水中所溶解了来自于铅，汞及其他重金属的毒性物质，这些毒性物质通常很难测量。
The toxic buildup of lead, mercury, and other heavy metals in the soil and water near coal plants and smelting factories is not usually measured.
最后一个选项不是必须的，特别是因为它的值很难测量，但希望限制打印图形密集型文件的用户的确可以利用这个选项。
The latter is not required, especially because it's a difficult value to gauge, but it does provide options for people who want to limit the printing of graphically intensive files.
在试验结果的获取中，为能够得到很难测量的线电极周围的放电间隙和工件形状数据，提出一种新的三维形状测量方法。
In order to obtain the 3D data of the discharge gap and workpiece shape from the experimental results, a new measurement is proposed.
Oken博士说，新的研究显示18个月的婴儿没有表现出DHA的助益作用可能是因为婴儿期的效果“很难测量”，或“可能是DHA的助益作用没有4岁时那样明显”。
Oken said the new study might have shown no benefit in 18-month-olds because effects in infants might be "hard to measure" or "it may be that the benefit of DHA is not as important as when you're 4.
很难定义，甚至更难测量一些可变因素，如记忆力、智力和情绪。
Variables such as memory, intelligence, or mood are hard to define and even harder to measure.
其结果是在太阳光球层中的锌、镓、铜恰好是很难测定的，那么我们对太阳的测量方法可能不是很正确。
It turns out that zinc, gallium, and copper are very difficult to measure precisely in the solar photosphere so our measurements of the sun may not be quite right.
其结果是在太阳光球层中的锌、镓、铜恰好是很难测定的，那么我们对太阳的测量方法可能不是很正确。
It turns out that zinc, gallium, and copper are very difficult to measure precisely in the solar photosphere so our measurements of the sun may not be quite right.
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