问题 问答题

由原子构成的物质,为什么对外不显电性?

答案

原子由带正电荷的原子核和核外带负电的电子构成,原子核是由带正电的质子与不带电的中子构成,原子核所带的电荷数与核外电子所带的电荷数相等,电性相反,整个原子不显电性.所以,由原子构成的物质不显电性.

故答为:原子由带正电荷的原子核和核外带负电的电子构成,原子核是由带正电的质子与不带电的中子构成,原子核所带的电荷数与核外电子所带的电荷数相等,电性相反,整个原子不显电性.所以,由原子构成的物质不显电性.

完形填空

阅读下列各小题,根据括号内的汉语提示,用句末括号内的英语单词完成句子。

小题1:Advertisements _____________ these facts have been printed in newspapers and magazines but have not helped much.   (base)

根据这些情况拟定的广告词登载在报纸和杂志上,但是效果不佳。

小题2:He only requested in the meeting that a program ________________ people who had been out of work for a long time.   (design)

他在会上提出的唯一要求是要为那些长久失去工作的人制定一个项目。

小题3:There is no doubt __________________ his injury in time for the race next week. (recover)

毫无疑问,他会及时恢复伤痛并参加下星期的比赛。

小题4:It took nearly two hundred years _________________ as an analytical machine by Charles Babbage.   (build)

差不多化了两百年查尔斯.巴比奇才把我制成了一台分析机。

小题5:Marty advised me to refer to some books with ___________________.   (familiar)

玛迪建议我去参考一些我不熟悉的书。

小题6:It was the second time that Bellinsky ________________by her boss, who was always strict in work.   (think)

贝林斯基第二次受到她老板的好评,他总是对工作一丝不苟。

小题7:Much attention __________________ the rare animals and plants from dying out.  (protect)

应该特别注意保护那些珍稀动植物以免灭绝。

小题8:Daisy has found that a lot of antelopes __________________ and killed for the wool beneath their stomachs.   (hunt)

黛茜发现很多藏羚羊在遭受捕获和杀戮以获取它们腹部的皮毛。

小题9:Only when he thought of his lovely daughter               his future during the hard days.   (hopeful)

在那艰苦的岁月里,只有想到他那可爱的女儿,他才对前途充满希望。

小题10:It was a palace outside St Petersburg where she spent her summers _____________.  (have)

她派人把它搬到了圣彼得堡郊外她避暑的宫殿里。

问答题 简答题