食管第2狭窄处()。
A.环咽肌收缩而成
B.由主动脉弓压迫食管所致
C.由左主支气管压迫食管所致
D.由右主支气管压迫食管所致
E.食管穿过横膈裂孔所致
参考答案:B
—How quiet it is here!
—Yes. We can hear nothing but the _____ of the running water.[ ]
A. music
B. sound
C. voice
D. noise
肺痨与虚劳的鉴别。