急性阑尾炎伴穿孔的最主要因素是
A．阑尾腔阻塞
B．阑尾壁受粪石压迫坏死
C．细菌的毒力
D．阑尾缺血
E．阑尾周围其他因素
参考答案：B
This is the rule ________ you must stick.[ ]
A. to which
B. to that
C. in which
D. on which
