题干
My physics teacher is ________ to spend much time ________ things to us.
A：patient enough; explain
B：enough patient; explaining
C：patient enough; explaining
D：enough patient; explain
答案(点此获取答案解析）
C
2NH3的反应，自反应开始至2s末，氨的物质的量由0变为0.8 mo
l，则以氢气的浓度变化表示该反应在2s内的平均反应速率是