题干
—Why haven’t you asked her to come here?
—She _______ an important experiment when I found her and she _____ it.
—She _______ an important experiment when I found her and she _____ it.
A：had done ; didn’t finish
B：was doing ; hasn’t finished
C：did ; wouldn’t finish
D：did; hadn’t finished
答案(点此获取答案解析）
B
，若函数
，
，有大于零的极值点，则（ ）
