使用课本所示型号的计算机，按键顺序是 ，最后显示的结果是（　　）

已知函数f（x）=1﹣$\frac{1}{\sqrt{x}}$，判断f（x）的单调性并运用函数的单调性定义证明．

· Finding：Seniors, on average, bathe fewer than 3 times a week. And nearly 30% wash their hands only 4 times a day - half of the number doctors advise.

· Step：We touch our faces around 3,000 times a day - often inviting germs（病菌）to enter our mouth, nose, and eyes. Use toilet paper to avoid touching the door handle. And, most importantly, wash your hands often with hot running water and soap for 20 seconds.

下列各项，加线成语使用恰当的一项是（   ）