呼吸骤停的原因有（）
A.创伤
B.会厌炎
C.心肌梗死
D.卒中
E.吸入烟雾
参考答案：A, B, C, D, E
There are many famous cultural relics in our country, many _______ thousands of years ago.
A．dating back to
B．date back to
C．dated back to
D．were dated back to
被太平洋、印度洋、大西洋包围的大洲是[ ]
A．亚洲
B．非洲
C．大洋洲
D．南极洲
