题干

据史料记载:“隋朝大业五年(609年),全国人口为四千六百多万;唐朝贞观十三年(639年)全国人口为一千二百多万;天宝元年(742年),全国人口为近五千一百万”。下列观点正确的是       (   )

A:隋炀帝的暴政和隋末战乱是人口锐减的主要原因

B:“开皇之治”较“贞观之治”成效更为显著

C:唐朝建立后改变了以人丁为主的赋役制度,促使人口逐渐增加

D:新农作物玉米等引进中国,使唐朝人口迅速增长

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答案(点此获取答案解析)

A

同类题4

从下面方框中选出10个单词,并将其正确形式填写在答题卡相应题号后,使短文意思正确通顺(每词限用一次)。

come    different    excite     go good    live      

loud     low      mean     nature time    west

    An old saying goes, “When in Rome(罗马),do as the Romans do.” I learned the ____ of this when I studied in Russia.

    One day I invited some of my Chinese friends to a famous local restaurant in Moscow. My guests and I were ____  from visiting Red Square and happy about our meeting. We had a warm  chat  until  the  waiter  told  me  that  we  were  being  too  loud.  We  turned  our  voices ____ .But this didn't last long. The waiter came over to us two more ____  with the same message.

    How bad an impression(印象) we must have left on the local people! In China, it's ____  and important for a host to make a ____  atmosphere(气氛).However, in Russia and ____  countries, having a meal in a public place means you must keep your voice low. You need to be polite to others.

    I felt bad about this. Even though we tried our ____ , it's very difficult to develop a new habit.

    Russians have their own special habits. My Russia friend, Andrey always looks around and thinks for a while before leaving home. I asked him why he did this. “Aha,” Andrey said, “in Russia, people always take about a minute ____  over things and plans in their minds before leaving. So they won't leave anything necessary behind.”

    Finding the ____  between cultures is much fun. I'd like to keep my eyes and mind open.

同类题5

如图是世界上第一个全超导核聚变“人造太阳”实验装置,能模拟太阳产生能量.为了达到聚变所要求的温度,需要用电流产生磁   场,电流的强度非常大,时间长了,线圈就要发热.从这个角度来说,装置不可能长时间运转.为了解决这个问题,人们把最新的超导技术引入到该装置中.

虽然“人造太阳”的奇观在实验室中已经出现,但“人造太阳”所发出的电能在短时间内还不可能进入人们的家中.根据目前世界各国的研究状况,这一梦想最快有可能在50年后实现.“人造太阳”的实验研究具有十分重大的战略意义.在过去的100年中,人类对能源的研究和使用已从化石燃料的单一化结构,发展到以化石能源为主,核能和水能互补的多元格局.但是,石油、煤炭等化石能源不能过度的开采和使用,目前已经商业化的核裂变能又会产生一定的核废料,同时受到原料的限制.

而核聚变能则被认为是无限、清洁、安全的换代新能源.据专家介绍,自然界最容易实现的聚变反应是氢的同位素﹣﹣氘和氚的聚变.氘在地球的海水中藏量丰富,多达40万亿吨,如果全部用于聚变反应,释放出的能量足够人类使用几百亿年,而且反应产物是无放射性污染的氦.这就是为什么世界各国,尤其是发达国家不遗余力,竞相研究、开发核聚能的原因所在.