“Why can’t you do it now?” “_____I’m too_爱下问搜题

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问题选择题

“Why can’t you do it now?” “_____I’m too busy.”

A．Since

B．As

C．Because

D．For

答案

答案：C

解答题

已知函数f(x)＝x³－3x²－9x＋11.

(1)写出函数f(x)的递减区间；

(2)讨论函数f(x)的极大值或极小值，如有试写出极值．(要列表求)

选择题

There are so many kinds of radios in the shop. I can’t decide _________.

A．to buy what

B．to buy which

C．which to buy

D．when to buy