题目

已知函数。    （1）求函数的单调递减区间；    （2）求切于点的切线方程；    （3）求函数在上的最大值与最小值。 答案：—Steve is good at writing short stories.—So he is. But he writes _______ than us. So he can't get good grades in writing. [     ]A. most carefullyB. more carefully C. less carefullyD. least carefully