氢氰酸中毒时可视黏膜的颜色为（）
A.鲜红
B.潮红
C.苍白
D.发绀
E.黄染
参考答案：A
As soon as I entered Evan's company I saw a board ________"________ to Evans".
A．reads; Welcomed
B．written; to Welcome
C．reading; Welcome
D．printed; Welcame
岩石隧道井下掘进每工日工作时间为（ ）小时。
A．6
B．7
C．8
D．24
