在社会变迁中，经济变迁包括( )。 A．生产力的变化 B．生产量的增长 C．生产质

什么是共济失调性脑性瘫痪?

“长跑、背单词、写日记”这些事情比较枯燥，但还应该强迫自己去做。因为 [ ]

A．通过做自己不感兴趣但有意义的事，有助于培养自己坚强的意志品质 

B．通过做这些事，能够减少娱乐时间，免受外界的不良影响 

C．做这些事情，可以调节自己的不良情绪 

D．通过做这些事，可使自己成为具有开拓进取精神的人 

在500米的高空，有一架飞机以40 m/s的速度水平匀速飞行，若忽略空气阻力的影响，取g＝10m/s²，tan37°=3/4

求：（1）从飞机上掉下来的物体，经多长时间落到地面；

（2）物体从掉下到落地，水平方向移动的距离多大；

（3）从掉下开始，第3秒末物体的速度。

Transportation and communication networks bring people together．Yet sometimes people themselves create barriers(障碍)to transportation and communication．

In some countries，laws stop people from moving freely from place to place．Over the centuries，many groups of people have been denied the freedom to travel because of their race，religion，or nationality．In the Middle Ages，for example，Jews were often forbidden to move about freely within certain cities．South Africa’s government used to require black Africans to carry passes when they travel within the country．Some governments require all citizens to carry identification papers and to report to government officials whenever they move．

Countries set up customs posts at their borders．Foreign travellers must go through a customs inspection before they are allowed to travel in the country．Usually travellers  have to carry special papers such as passports and visas(签证)．Some countries even limit the number of visitors to their country each year．Others allow tourists to visit only certain areas of the country，or they may require that travellers be with an official guide at all times during their stay．

Many of those barriers to travel also act as barriers to communication．When two governments disagree with each other on important matters，they usually do not want their citizens to exchange news or ideas freely．Countries often try to keep military or lndustrial information secret．

Today，people have the ability to travel，to communicate，and to transport goods more quickly and easily than ever before．Natural barriers that were difficult or dangerous to cross a hundred years ago can now be crossed easily．The barriers that people themselves make are not so easy to overcome．But in spite of all the different kinds of barriers，people continue to enjoy travel and the exchange of goods and ideas.

小题1:Choose the best title for the passage．

A．Progress of Human Society

B．Restrictions on Transportation

C．Functions of Communication

D．Barriers Made by People小题2:The author uses the examples in the second paragraph to tell people that_______.

A．travellers have to carry special papers such as visas

B．customs posts are necessary at the borders of the countries

C．people have been allowed to travel freely within the country

D．people have not been permitted to travel freely for various reasons小题3:Why do some governments limit the freedom of communication?Because they______.

A．intend to keep their national secrets unknown to others

B．think such freedom will lead to wars

C．often disagree with each other on important matters

D．want to show their authority over communication小题4:We may learn from the passage that_______.

A．people do not care about the removal of barriers between countries

B．people can not remove the obstacles made by themselves

C．man-made barriers are sometimes harder to overcome than natural ones

D．barriers should be taken for granted as they always exist

药物归经的依据是（）

A.五味入五脏

B.脏腑经络理论

C.药物的质地

D.药物作用于人体的治疗范围

E.药物升降浮沉性能