下列烯烃中哪一个最稳定？（）
A.A
B.B
C.C
D.D
参考答案：C
---_________?
---She is a shop assistant in the biggest mall.
A．How old is your sister
B．What’s the matter with your sister
C．Where does your sister work
D．What does your sister do?
在html的段落标志中，标注文件子标题应使用（）
A、<PRE><PRE>
B、<P>
C、<HN><HN>
D、<BR>
