[单选题]《煤矿安全规程》规定矿井空气体积中NH3的最高允许浓度是( )%。
A.0.04
B.0.004
C.0.0004

It was the worst tragedy in maritime (航海的) history, six times more deadly than the Titanic. When the German cruise ship Wilhelm Gustloff was hit by torpedoes (鱼雷) fired from a Russian submarine in the final winter of World War II, more than 10,000 people—mostly women, children and old people fleeing the final Red Army push into Nazi Germany—were packed aboard. An ice storm had turned the decks into frozen sheets that sent hundreds of families sliding into the sea as the ship tilted and began to go down. Others desperately tried to put lifeboats down. Some who succeeded fought off those in the water who had the strength to try to claw their way aboard. Most people froze immediately." I’ll never forget the screams," says Christa Ntitzmann, 87, one of the 1,400 survivors. She recalls watching the ship, brightly lit, slipping into its dark grave and into seeming nothingness, rarely mentioned for more than halt a century.
Now Germany’s Nobel P
A. a strong ice storm tilted the ship.
B. the cruise ship sank all of a sudden.
C. the badly damaged ship leaned toward one side.
D. the frightened passengers fought desperately for lifeboats.