题干
-----Do you think we should accept that offer?
-----Yes, we should, for we such bad luck up till now, and time_________ out.
A：have had; is running
B：had; is running
C：have; has been ru
D：have had; has been ru
答案(点此获取答案解析）
A
改写成数值比例尺是
，若函数
，
，有大于零的极值点，则（ ）