哪些情况要考虑嗜铬细胞瘤的可能

A．阵发性高血压伴有心动过速、心慌、四肢冰冷

B．排尿或大便时引起高血压症状发作或晕厥

C．高血压伴腹部包块，按摩包块引起高血压发作

D．高血压经多种降压药物治疗无效

E．多次发作高血压危像而肾功能损害不明显，眼底变化不严重者

If you hear the firing of a gun at one minute intervals from another vessel，this indicates that（）.

A.the gun is being used to sound passing signals

B.the vessel is in distress

C.all vessels are to clear the area

D.all is clear and it is safe to pass