-- I'm sorry ________ you that I have made your book wet.
-- _______ It can become dry quickly.
A:tell; Well done.
B:tell; Don't worry about it.
C:to tell; Don't worry about it.
D:to tell; Well done.
当黑龙江省冰天雪地时,海南岛依然百花盛开,这是因为我国( )
已知函数 f(x)=(1−k)x+1ex .
(Ⅰ)如果f(x)在x=0处取得极值,求k的值;
(Ⅱ)求函数f(x)的单调区间;
(III)当k=0时,过点A(0,t)存在函数曲线f(x)的切线,求t的取值范围.
水可以造福人类,但水被污染后却会给人类造成灾难。为了防治水的污染,下列各项:①清除水中所有动、植物;②不任意排放工业废水;③禁止使用农药和化肥;④生活污水经过净化处理后再排放;⑤禁止生产和使用含磷的洗衣粉。其中可以采用的方法是( )