问题 单项选择题

在计算机的浮点数表示中,主要影响数值表示范围的是()。

A.阶码的位数

B.尾数的位数

C.规格化的方法

D.尾数下溢的处理

答案

参考答案:A

解析:

浮点表示法是指把一个数的有效数字和数的范围在计算机的一个存储单元中分别予以表示。这种把数的范围和精度分别表示的方法中,数的小数点位置随比例因子的不同而在一定范围内自由浮动。

一个机器浮点数由阶码、尾数及其符号位组成。其中,阶码用整数形式表示,指明小数点在数据中的位置,决定了浮点数的表示范围;尾数用定点小数表示,给出有效数字的位数,决定了浮点数的表示精度。换言之,在计算机的浮点数表示中,主要影响数值表示范围的是阶码的位数,影响计算精度的是尾数的位数。

阅读理解

When I was young, I had an old neighbor named Dr. Gibbs. He didn’t look like any doctor I’d ever known. He never shouted at us for playing in his yard. I remembered him as a neighbor who was nicer than anyone else in the neighborhood.

When Dr. Gibbs was happy, he was planting trees. And his life’s goal was to make it a forest.

Dr. Gibbs had some interesting theories about planting. He talked about trees that weren’t watered would grow deep roots in search of water. So he never watered his trees. He planted an oak (橡树) and, instead of watering it every morning, he beat it with the rolled-up newspaper. I asked him why he did that, and he said it was to get the tree’s attention.

Dr. Gibbs died a couple of years. Every now and again, I walk by his house and look at the trees that he planted twenty-five years ago. They’re very strong now.

I planted a couple of trees a few years later. I watered them regularly and took good care of them. Whenever a cold wind blows, they shake their leaves and branches.

The funny thing about those trees of Dr. Gibbs was that difficulty seemed to help them in ways comfort and ease never could.

小题1:What was Dr. Gibbs’ life goal?

A.To build a forest.

B.To save more lives.

C.To make a lot of money.

D.To study plants.小题2:One of Dr. Gibbs’ theories about planting was that ______.

A.he often talked to the trees

B.he kicked the trees heavily

C.he never watered the trees

D.he buried the leaves around the roots小题3:What does the writer mainly want to tell us?

A.Trees are not as weak as we think.

B.We should listen to others’ advice.

C.Difficulty is necessary for growth.

D.Planting trees is good for the environment.

多项选择题