人体组织和体液中,下列哪一项最能使声衰减程度加重
A.胆汁、尿液、血液
B.皮下脂肪
C.肝肾实质、肌肉
D.胶原纤维
E.钙质
参考答案:E
_____________ play on the street! It's dangerous. [ ]
A. Don't
B. Not
C. Please
D. No