题干
—Don't forget to take an umbrella with you. It's going to rain.
—OK. I'll take it.
A：Plan
B：Remember
C：Refuse
答案(点此获取答案解析）
B
2NH3，3 min后测得密闭容器内的压强是起始时的0．9倍，在此时间内v(H2)是( )