题干

一般的物体都有热胀冷缩现象,当物体受热膨胀时,它的密度(   )

A:不变

B:增大

C:减小

D:都有可能

上一题 下一题 0.0难度 选择题 更新时间:2011-05-11 04:32:10

答案(点此获取答案解析)

C

同类题2

阅读下面的文章,完成小题。

时间怎样地行走

迟子建

    墙上的挂钟,曾是我童年最爱看的一道风景。

    我对它有一种说不出的崇拜,因为它掌管着时间,我们的作息似乎都受着它的支配。我觉得左右摇摆的钟摆就是一张可以对所有人发号施令的嘴,它说什么,我就得乖乖的听。到了指定的时间,我们得起床上学,得做课间操,得被父母吆喝着去睡觉。

    虽然说有的时候我们还没睡够不想起床,我们在户外的月光下还没有戏耍够不想回屋睡觉,但都必须因为时间的关系而听从父母的吩咐。他们理直气壮呵斥我们的话与挂钟息息相关:“都几点了,还不起床!”要么就是:“都几点了,还在外面疯玩,快睡觉去!”

    我那时天真地以为,时间是被一双神秘的大手放在挂钟里的,从来不认为那是机械的产物。

    它每时每刻地行走着,走得不慌不忙,气定神凝。它不会因为贪恋窗外鸟语花香的美景而放慢脚步,也不会因为北风肆虐、大雪纷飞而加快脚步。它的脚,是世界上最能禁得起诱惑的脚,从来都是循着固定的轨迹行走。我喜欢听它前行的声音,总是一个节奏,好像一首温馨的摇篮曲。

    我上初中以后,手表就比较普及了。我看见时间躲在一个小小的圆盘里,在我们的手腕上跳舞。它跳得静悄悄的,不像墙上的挂钟,行进得那么清脆悦耳,“滴答——滴答——”的声音不绝于耳。所以,手表里的时间总给我一种鬼鬼祟祟的感觉,少了几分气势和威严。所以明明到了上课时间,我还会磨赠一两分钟再进教室,手表里的时间也就因此显得有些落寞。

    后来,生活变得丰富多彩了,时间栖身的地方就多了。项链坠可以隐藏着时间,台历上镶嵌着时间,玩具里放置着时间,至于电脑和手提电话,只要我们一打开它们,率先映入眼帘的就有时间。时间如繁星一样到处闪烁着,它越来越多,也就越来越显得匆匆了。

    十几年前的一天,我第一次发现了时间的痕迹。我在梳头时发现了一根白发,它在清晨的曙光中像一道明丽的雪线一样刺痛了我的眼睛。我知道时间其实一直悄悄地躲在我的头发里行走,只不过它这一次露出了痕迹而已。

    时间让一棵青春的小树越来越枝繁叶茂,让车轮的辐条越来越沾染上锈迹,让一座老屋逐渐驼了背。时间好似变戏法的魔术师,它能让一个活生生的人瞬间消失在他们辛勤劳作过的土地上,我的祖父、外祖父和父亲,就让时间给无声地接走了,再也看不到他们的脚印,只能在清冷的梦中见到他们依稀的身影。他们不在了,可时间还在,它总是持之以恒激情澎湃地行走着——在我们看不到的角落,在我们不经意走过的地方,在日月星辰中,在梦中。

    我终于明白挂钟上的时间和手表里的时间只是时间的一个表象而已,它存在于更丰富的日常生活中。只要我们在行走,时间就会行走。我们和时间如同一对伴侣,相依相偎着,不朽的它会在我们不知不觉间,引领着我们一直走到地老天荒。

同类题3

阅读理解

    The Nazca Lines are a series of large ancient geoglyphs (地画) in the Nazca Desert, in southern Peru. It is ranging from geometric patterns to drawings of different animals and stylized human-like forms. The ancient lines can only be truly taken in from high in the air, leaving generations puzzled as to how these precise works could have been completed long before the documented invention of human flight.

    The Lines were first spotted when commercial airlines began flying across the Peruvian desert in the 1920,s. Who built them and what was their purpose? Are they roads, star pointers,maybe even a gigantic map? If the people who lived here 2,000 years ago had only a simple technology, how did they manage to construct such precise figures? Did they have a plan? These markings are like a vast puzzle.

    The Nazca Lines are the most outstanding group of geoglyphs in the world. There are also huge geoglyphs in Egypt, Malta,United States (Mississippi and California), Chile,Holivia and in other countries. But the Nazca geoglyphs, because of their numbers, characteristics, dimensions and cultural continuity as they were made and remade throughout a certain history period, form the most impressive archeological (考古学的) group.

    The Nazca plain is unique for its ability to preserve the markings upon it, due to the combination of the climate (one of the driest on Earth, with only twenty minutes of rainfall per year) and the flat, stony ground which minimizes the effect of the wind at ground level. With no dust or sand to cover the plain and little rain or wind to erode (腐蚀) it, lines drawn here tend to stay drawn. These factors, combined with the existence of lighter-colored subsoil beneath the desert surface, provide a vast writing pad that is suited to the artist who wants to leave his mark eternal.