题型:选择题 I know nothing about the news _____ my friend told me yesterday.[ ]A. because B. sinceC. until D. after 查看答案
题型:多项选择题 利用串联通风的被串联采煤工作面进风巷甲烷传感器的()。A、报警浓度为≧0.5%CH4B、断电浓度为≧0.5%CH4C、复电浓度为<0.5%CH4D、断电浓度为≧1.0%CH4 查看答案