问题 单项选择题

以下关于父进程和子进程的叙述中,不正确的是______。

A.父进程创建子进程,因此父进程执行完之后,子进程才能运行
B.父进程和子进程之间可以并发执行
C.父进程可以等待所有子进程结束后再执行
D.撤销父进程时,可同时撤销其子进程

答案

参考答案:A

解析: 本题考查操作系统基础知识。
在操作系统中,进程是资源分配的基本单位,也是独立运行的基本单位,进程是程序在一个数据集合上的运行过程,是系统进行资源分配和调度的一个独立单位。一个进程可以创建若干个子进程,子进程被创建后,一般与父进程并发执行,以完成特定的任务;父进程创建完子进程后,也可以等待所有子进程结束后再执行;但当撤销一个进程时,操作系统会检查被撤销进程是否有子孙进程,若有子孙进程,还应撤销该进程的子孙进程。当父进程执行完之后被撤销时,子进程也被一同撤销。

单项选择题
阅读理解

A new reading tool was put on the market this week for the two-to five-year-old set. It is sold for at least $389, an expensive purchase for a kid – and that doesn’t even include a $99 annual subscription (订阅) fee for games, e-books, and age-appropriate software.

That might be fine for parents willing and able to pay thousands for private nursery schools, but will the tool actually help kids learn language and reading skills more effectively than traditional books?

Probably not, said Dr. Michael Rich, director of the Center for Media and Child Health at Children’s Hospital Boston. “There is a sensory components (感官因素) to books that isn’t there with e-books,” he explained. “You can smell it, turn the pages, and taste it, as young kids are likely to do.”

That might help little ones become more familiar with the books, helping them learn from them, but far more important is whether a person is actually sitting with them while they’re looking at the pages.

Researchers have shown time and again that kids learn better when they’re having interaction (互动) with real people, rather than electronic voices reading to them from a computer or speaking to them from the TV.

A Georgetown University study found that kids who learned to put on gloves from watching a video took six times as long to learn the process as those who watched it shown by an adult standing in front of them.

“I’m a big believer in teaching kids to live in the digital society and use what the rest of the family uses, but they do need to be supervised,” said Dr. Gwenn O’Keeffe, a Boston-based children’s doctor and spokesperson for the American Academy of Pediatrics. “We don’t recommend that young kids use any type of technology for very long since they have the attention span (注意力持续时间) of a butterfly.”

小题1:According to the text, the new tool        .

A.is mainly used to entertain kids

B.can be accepted by most families

C.is designed for preschool kids

D.can download games for free小题2:Why is Dr. Michael Rich against the new tool?

A.Because it doesn’t really involve many of the senses.

B.Because it does great harm to kids’ eyesight.

C.Because kids can’t communicate with it.

D.Because traditional books are cheaper.小题3:The study mentioned in Paragraph 6 aims to        .

A.show the disadvantage of kids’ watching videos

B.prove the importance of interaction with people

C.ask parents to teach their kids to learn

D.prove using e-books saves much time小题4:The underlined word “supervised” in the last paragraph can be replaced by “     ”.

A.punished

B.watched

C.encouraged

D.understood小题5:What is the author’s purpose in writing the text?

A.To introduce a new electronic device.

B.To teach kids how to live in a digital world.

C.To show parents how to help kids gain knowledge.

D.To throw new light on kids’ use of electronic tools.