提示胃穿孔最有意义的根据是（）
A.突然腹痛
B.急性腹膜炎体征
C.休克征象
D.腹腔试验性穿刺
E.气腹征象
参考答案：E
Although many modifications have been made in it, the game known in the United States as football can be traced directly to the English game of rugby.
A．rules
B．changes
C．demands
D．leagues
请从下列选项中指出导游人员要劝阻旅游者自由活动的几种情况：（）
A．旅游团即将离站时
B．旅游者已经劳累时
C．影响旅游计划顺利进行时
D．存在不安全因素时
E．导游认为不宜旅游者自由活动时
