骨囊肿可以自愈，保守治疗无效时可行刮除植骨术。()
参考答案：对
溃疡病急性穿孔最有诊断意义的是（）。
A．腹痛突然加重
B．出现腹膜炎体征
C．肠鸣音减弱或消失
D．休克征象
E．气腹征
In a crossing situation，the stand-on vessel should normally（）.
A.take action to cross ahead of the other vessel
B.take action to pass astern of the other vessel
C.maintain course and speed
D.change course and increase speed
