题目

.— Has Tom finished his report so far?        — I have no idea.He ______it this morning.        A.did                    B.has done        C.was doing           D.had done 答案:C已知函数.(Ⅰ)当时,求曲线在点处的切线方程;(Ⅱ)求的单调区间;(Ⅲ)若在区间上恒成立,求实数的取值范围.
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