封闭楼梯间的门必须采用乙级防火门。
参考答案：错
-----Look at the sign. It _________ “No smoking”. ----Oh, sorry, I did not see it.
A．says
B．writes
C．shows
D．Appears
在横线上填上“＞”“＜”或“=”
69800______68900 二亿______20000万
12×20______40×80 274680030______274860030
46×20______1000 1000000______十万．
