在采掘工作面回风巷风流中CO2浓度超过1.5时必须停止工作，撤出人员，制订措施，进行处理。
参考答案：对
为什么测风时应先将风表空转30s？
What’s not true about Trust-mart().
A. It’s a Taiwanese supermarket chain.
B. The world largest retailer has agreed to buy Trust-Mart.
C. Wal-Mart will buy Trust-Mart for 1 billion yuan.
D. Buying Trust-Mart will make Wal-Mart the biggest food and department store network in China.
