题干
—That's a nice mobile phone.
—It is. My aunt __________ it for my last birthday.
A：buy
B：will buy
C：have bought
D：bought
答案(点此获取答案解析）
D
—That's a nice mobile phone.
—It is. My aunt __________ it for my last birthday.
A：buy
B：will buy
C：have bought
D：bought
2C（气）在最初0.2s内，消耗A的平均速率为0.06mol·（L·S）-1．则在0.2s时，真空箱中C的物质的量是