Sometimes they are fairly obvious to the trained eye.

有时候，如果受过训练的话，还是挺容易分辨的。

There are no scientific tests, only the trained eyes and hands of experts.

没有进行科学的测试，只凭专家" 阅物无数" 的眼睛和双手就可以确定。

He knew he knew nothing, and had not the trained eye or the keen instinct that trusted itself; but he was curious, as he went on, to find out how much others knew.

他知道自己什么都不知道，也没有训练有素的眼睛或相信自己的敏锐直觉；但随着他的继续，他很好奇，想知道其他人知道多少。