问题
选择题
The Education Department says that school safety has set off alarm bells with frequent reports of serious
accidents ________ students got injured or killed.[ ]
A．after which
B．in which
C．by which
D．for which
答案
答案：B
缺失，
残根，根断面平龈缘，根稍短，欲设计为
烤瓷固定义齿修复，其理由是（）。