下列哪项不是喘的症状特点（）
A.呼吸困难
B.张口抬肩
C.鼻翼扇动
D.呼吸急迫
E.喉间痰鸣
参考答案：E
已知线段AB=2cm，延长AB到C，BC=2AD，若D为AB中点，则线段DC的长为______cm．
What does the passage mainly discuss
A．Why historical archaeology was first developed.
B．How the methods and purpose of historical archaeology have changed.
C．The contributions architects make to historical archaeology.
D．The attitude of professional archaeologists toward historical archaeology.
