题干

如图所示,沿光滑的竖直墙壁用网兜把一个足球挂在A点.当悬线AB变短时,下列说法中正确的是(   )

A:球对墙的压力变大

B:球对墙的压力不变

C:悬线的拉力变小

D:悬线的拉力变大

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答案(点此获取答案解析)

A,D

同类题1

阅读下面文言文,完成文后各题。

        章频,字简之,建州浦城人。与弟頔皆以进士试礼部预选,会诏兄弟毋并举,频即推其弟,弃去。后六年,乃擢第。自试秘书省校书郎、知南昌县,改大理寺丞、知九陇县,迁殿中丞。眉州大姓孙延世伪为券夺族人田,久不能辨,转运使使按治之。频视券墨浮朱上,曰:“是必先盗印然后书。”既引伏,狱未上,而其家人复诉于转运使,更命知华阳县黄梦松覆按,无所异。梦松用此入为监察御史,频坐不时具狱,降监庆州酒,徙知长洲县。天禧初,增置谏官、御史十二人,频以选得召对,称旨,擢监察御史。陈、亳间民讹言兵起,老幼皆奔,命安抚京西。还,为三司度支判官。青州麻士瑶杀从子温裕,并其财,遣往按治,士瑶伏诛。又诏鞫邛州牙校讼盐井事。皇城使刘美依倚后家受赇使人市其狱频请捕系真宗以后故不问忤旨出知宣州改殿中侍御史迁侍御史频雅善丁谓,谓贬,左迁尚书比部员外郎、监饶州酒。起知信州,进刑部员外郎、知福州。王氏时,赋民官田,岁输租税而已。至是,或谓鬻之可得缗钱二十余万,频疏以为不可。徙知潭州。改广西转运使,擿宜州守贪暴不法,既罢去,反讼频子许尝被刑,而冒奏为秘书省校书郎,频坐谪知饶州。复入为度支判官,累迁刑部郎中。使契丹,至紫濛馆卒。契丹遣内侍就馆奠祭,命接伴副使吴克荷护其丧,以锦车驾橐驼载至中京,敛以银饰棺,又具鼓吹羽葆,吏士持甲兵卫送至白沟。诏遣其子访乘传扈其柩以归。访官三班奉职,即许也。

(节选自《宋史·章频传》)

同类题5

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    One of the main challenges facing many countries is how to maintain their identity in the face of globalization and the growing multi-language trend. "One of the main reasons for economic failure in many African countries is the fact that, with a few important exceptions, mother-tongue education is not practiced in any of the independent African states." said Neville Alexander, Director of the Project for the Study of Alternative Education in South Africa at the University of Cape Town.

    In response to the spread of English and the increased multi-language trends arising from immigration, many countries have introduced language laws in the last decade. In some, the use of languages other than the national language is banned in public spaces such as advertising posters. One of the first such legal provisions(规定) was the 1994 "Toubon law" in France, and the idea has been copied in many countries since then. Such efforts to govern language use are often considered as futile by language experts, who are well aware of the difficulty in controlling fashions in speech and know from research that language switching among bilinguals is a natural process.

    It is especially difficult for native speakers of English to understand the desire to maintain the "purity" of a language by law. Since the time of Shakespeare, English has continually absorbed foreign words into its own language. English is one of the most mixed and rapidly changing languages in the world, but that has not been a barrier to acquiring superiority and power. Another reason for the failure of many native English speakers to understand the role of the state regulation is that it has never been the Anglo-Saxon way of doing things. English has never had a state-controlled authority for the language, similar, for example, to the Academic Francaise in France.

    The need to protect national languages is, for most western Europeans, a recent phenomenon—especially the need to ensure that English does not unnecessarily take over too many fields. Public communication, education and new ways of communication promoted by technology, may be key fields to defend.