题干
—I’m afraid I couldn’t go to your birthday party.I have a test next Monday.
—Oh， ！You’re my best friend and you must be there！
—Oh， ！You’re my best friend and you must be there！
A：go ahead
B：come o
C：you needn’t
D：it doesn’t matter
答案(点此获取答案解析）
B
2NO+O2在体积不变的密闭容器中反应，达到平衡状态的标志是
