题干
— Mum, we're going to visit an old town this weekend.
— ________!
A：Have a good trip
B：That's OK
C：Not at all
D：Goodbye
答案(点此获取答案解析）
A
— Mum, we're going to visit an old town this weekend.
— ________!
A：Have a good trip
B：That's OK
C：Not at all
D：Goodbye
cZ(g)在一定温度下的密闭容器内达到平衡后，t0时改变某一外界条件，化学反应速率(v)—时间(t)图象如下图。下列说法正确的是（ ） 
