问题 单项选择题

在缺省用户目录下创建一个新用户alex的Linux命令是()(62)。

A.

B.

C.

D.

答案

参考答案:A

解析:

本题考查Linux系统中useradd命令的使用。

useradd命令用来建立用户账号和创建用户的起始目录,使用权限是超级用户。其语法格式为:

主要参数为:

●-c:加上备注文字,备注文字保存在passwd的备注栏中。

●-d:指定用户登录时的起始目录。

●-D:变更预设值。

●-e:指定账号的有效期限,缺省表示永久有效。

●-f:指定在密码过期后多少天即关闭该账号。

●-g:指定用户所属的群组。

●-G:指定用户所属的附加群组。

●-m:自动建立用户的登录目录。

●-M:不要自动建立用户的登录目录。

●-n:取消建立以用户名称为名的群组。

●-r:建立系统账号。

●-s:指定用户登录后所使用的shell。

●-u:指定用户ID号。

故在缺省用户目录下创建一个新用户alex的Linux命令是。

阅读理解

A new study warns that about thirty percent of the world’s people may not have enough water by the year 2025.

An American organization called Population Action International did the new study. It was more than three hundred and thirty-five million people lack enough water now. The people live in twenty-eight countries. Most of the countries are in Africa or in the Middle East.

Population Action International researcher Robert Engelman says by the year 2025, about three thousand million people lack water. At least 18 more countries are expected to have serious water problems. The demand for water keeps increasing. Yet the amount of water on the earth the same. Mr Engelman says the population in countries that lack water is growing in these countries will continue to increase.

The report says lack of water in the future may result several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr Engelman says there are problems all over the world because of diseases such as cholera that are carried in water.

Lack of water also may result in more international conflict. Countries may have to fight for water in the future. Some countries, such as Syria, Sudan, Cambodia, and so on, now get sixty percent of their fresh water from other countries. And the report says lack of water would affect the ability to improve their economies. This is because industries often need a large amount of water.

The Population Action International study gives several ways to solve the water problem. One way is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third is to use less water for agriculture. The report also says long-term solutions to the water problem must include controls on population growth.

小题1:According to the report, how many countries will lack water by the year 2025?

A.More than eighteen

B.About twenty-eight

C.Less than forty

D.At least forty-six小题2:____ million will lack water by the year 2025?

A.335

B.3,000

C.3,305

D.355小题3:Which of the following is NOT true according to the passage?

A.The amount of the water on earth will always stay the same.

B.The report gives three solutions to water problem.

C.M ost of the countries that lack water belong to the developing ones.

D.There’s only one long-term solution to solve the water problem, that is we must try our best to control the population growth.小题4:The passage mainly tells us that_____.

A.water is very important for any people

B.PAI did a lot of study about water shortage

C.water shortage will be a serious problem facing us in the near future

D.controlling the population is the best way to solve the problem of water shortage

单项选择题