These fans arrived very early. They could see their favorite stars. (合并成一个句子)
These fans arrived very early ____ they could see their favorite stars.
We can't be late _________ class.
一定温度下,向a L密闭容器中加入2 mol NO2(g),发生反应:2NO2 2NO+O2,此反应达到平衡状态时的标志是( )