可引起高度呼吸困难的是
A．开放性气胸B．张力性气胸C．两者均有D．两者无
参考答案：C
痔形成的因素中，下列哪项是错误的
A．无静脉瓣B．直肠上、下静脉丛畸形C．静脉壁薄弱，结缔组织萎缩缺乏支持D．腹压增高E．直肠肛管慢性感染
Which of the following is true according to the speaker
A．There are some questions if we start over.
B．We should do it again.
C．It’s impossible to do it again.
D．We should start over.
