A technique originally developed for detecting air pollutants, called proton-induced x-ray emission, which can quickly analyze the chemical elements in almost any substance without destroying it, is finding uses in medicine, archaeology, and criminology. og:解释说called protin-induced X-ray emission should be placed next to a technique and should not be set off by commas; relative clause introduced by which incorrectly and illogically modifies emission. 定语从句which为什么要去掉逗号,我没看懂,求助~~ |