股骨颈骨折常见的晚期并发症是（）
A.髋关节强直
B.髋关节僵硬
C.股骨头坏死
D.骨化性肌炎
E.泌尿系感染
参考答案：C
The reason _____ he pretended to sleep in class was quite different from the one _____ you explained to me. [ ]
A. that; why
B. why; that
C. that; which
D. why; why
简述生产性毒物的分类？
