矿井空气中主要有害气体有哪些？
参考答案：
矿井空气中主要有害气体有一氧化碳、二氧化碳、二氧化氮、二氧化硫、硫化氢、甲烷、氨等。
It has been estimated that the earth's surface temperature has increased one quarter to three quarters of a degree since 1805.
A．to
B．by
C．at
D．with
简述中华书局主要成绩。
