A：任意一个命题都有逆命题
B：定理“全等三角形的对应角相等”有逆定理
C：正方形都全等是假命题
D：“画平行线”不是命题
A. Let me see. I think it's a toilet for a pet（宠物）.
B. Yes. I do. I like studying them.
C. Do you know anything about the public signs?
D. OK. What does that sign on the door mean?
每天吸烟数量(支)
1-10
11-20
21-30
31-40
41以上
吸有过滤嘴的
肺癌发病率%
15
30
40
60
80
吸无过滤嘴的
20
35
57
87
90
