煤气的爆炸极限实际上是浓度指标。
参考答案:对
—Why was that performance put on?
—_____ him for his contributions _____ our country.
A.Honor; for
B.Honoring; for
C.To honor; to
D.By honoring; to
人在做梦的时候,大脑处于()状态
A.快速眼动睡眠
B.非快速眼幼睡眠
C.快速眼动睡眠状态与非快速眼幼睡眠状态同时存在`
D.两者均不是