强直性脊柱炎的原发病变是
A．关节软骨
B．滑膜
C．肌腱和关节囊的骨附着处
D．韧带
E．软骨下骨
参考答案：C
A group of store managers must assemble 280 displays for an upcoming sale. If they assemble 25 percent of the displays during the first hour and 40 percent of the remaining displays during the second hour, how many of the displays will not have been assembled by the end of the second hour ？（）
A.70
B.98
C.126
D.168
E.182
提高挖掘机生产能力的途径有哪些？
