题目

It is reported that the government has _________ the outbreak of violence by sending a large group of soldiers to police the area.        A. gone for                   B. reacted to                 C. appealed to               D. made for 答案：B将20克甲、5克乙、8克丙三种纯净物混合，在密闭容器中加热发生化学反应，经分析可知：反应后混合物中含有5克甲、16克丙，还含有一种新物质丁．则丁物质的质量是（ ）A．12gB．9gC．4gD．17g