热水气排气管穿墙部位与墙间的间隙应密封，是为了防止（）。
A.烟气回流入室
B.烟气滞留
C.烟气外泄
D.烟气排放
参考答案：A
― How do you like your English professor?
― He has lots of interesting _____ abroad, and in a word, he is a teacher of rich ____.[ ]
A. experiences, experiences
B. experience, experience
C. experiences, experience
D. experience, experiences
影响股份变动后持有期收益率的因素有（）。
A.现金股息
B.股票买入价
C.股票拆分
D.股票卖出价
