铁路隧道围岩分级中,()最适合工程建设。
A.Ⅰ级
B.Ⅱ级
C.Ⅲ级
D.Ⅳ级
参考答案:A
While he was at college,he took part in political activities,and was thrown into prison.
A.the;/
B./;the
C./;/
D.the;the
干粉灭火剂的添加剂中没有下面()。
A、硅油
B、流动促进剂
C、锌
D、防结块剂