与非吸烟者相比吸烟者死于肺癌的风险提高多少倍？
参考答案：
6---13倍
Let's ________ the picture ________ Lucy and Lily. [ ]
A. show; from
B. show; to
C. to show; to
D. to show; from
盾构距接收井井壁封门约（）cm时，应停止掘进，对封门处土体完成加固后，进行封门拆除。
A.10
B.20
C.40
D.50
