问题 选择题

下列日常生活中常见的四种物质,其中属于氧化物的是(  )

A.液态氧

B.铝合金

C.食醋

D.干冰

答案

A、液态氧是由氧元素组成的纯净物,属于单质.故选项错误;

B、铝合金是由铝和其它物质组成的,属于混合物.故选项错误;

C、食醋中含有水和醋酸,属于混合物.故选项错误;

D、干冰是由碳元素和氧元素组成的化合物,属于氧化物.故选项正确.

故选D.

阅读理解

Napping(小睡) after learning something new could help improve your memory--- as long as you dream, scientists say.

They found people who dream about a new task do it better on waking than those who do not sleep or do not dream.

Volunteers were asked to learn the layout(布局,设计) of a 3D computer maze(迷宫) so they could find their way several hours later. Those allowed to take a pap and who also remembered dreaming of the task, found their way to a landmark quicker.

The researchers think the dreams are a sign that unconscious(无意识的) parts of the brain are working hard to process information about the task..

Dr. Robert Stickgold of Harvard Medical School, said dreams may be a marker that the brain is working on the same problem at many levels.

Study tips

Co-author Dr. Erin Wamsley said the study suggests our non-conscious brain works on the things that it deem(认为) are the most important.

“Every day we are gathering lots of information and new experiences,” she said. “It would seem that our dreams are asking the question, “How do I use this information to inform(影响) my life?”

The scientists say there may be ways to use this phenomenon(现象) for improving learning and memory. For example, students might be better studying hard before bedtime, or taking a nap after a period of afternoon study.

小题1: Scientists say ______ could help improve your memory.

A.dream

B.nap

C.nap and dream

D.nap without dream小题2: What were volunteers asked to do?

A.Take a nap.

B.Dream a task.

C.Learn about 3D computer.

D.Find their way out of a maze.小题3:Which is right about dreams?

A.They are a sign that parts of the brain is unconscious.

B.They can help us fall asleep and improve learning and memory.

C.They tell us how to use this information to inform our life.

D.They may be a marker that the brain is working on the same problem.小题4:When is the best time for study?

A.Before bedtime.

B.After bedtime.

C.Before taking a nap.

D.In the afternoon.

单项选择题