超声波的人射角恒等于反射角。
参考答案:错
下列哪种病变引起的胸痛常沿一侧肋问神经分布
A.胸肌劳损
B.流行性胸痛
C.颈椎病
D.带状疱疹
E.皮下蜂窝织炎
Halliday described seven basic functions that language performs. Please write out any five of them.