题目

Moreover, __________you may hardly believe, the examiners had decided in advance to fail half the students taking part in the exams. A. which       B. that       C. who       D. whom 答案：A将SiCl4与过量的液氨反应可生成化合物Si(NH2)4。将该化合物在无氧条件下高温灼烧，可得到氮化硅（Si3N4）固体，氧化硅是一种新型的耐高温、耐磨材料，在工业上有广泛的应用。则氮化硅所属的晶体类型是(      )                             A.　原子晶体　　B.　分子晶体     C.　离子晶体　　D.　金属晶体