男性，70岁。烦躁失眠，吵闹不安，继而嗜睡。血气分析：pH 7.30，PaCO277

读美国略图，完成问题。

（1）A_______洋，B_______洋，C_________河，它仅次于非洲的________河，南美洲的________河和中国的________，是世界第四长河。

（2）D_________湖；E____   __山脉，它是________山系的北段．F__________山脉。

（3）美国位于________半球（东、西），领土共有________个州，其中位于有极昼极夜现象地区的是______州，有阳光直射现象的是___________州。

（4）美国的气候以________________为主，降水受_______影响显著，分布规律是_____________________。

小东上午7时25分从家出发，7时40分来到学校，他在路上用了______分．

Migration is usually defined as "permanent of sempermanent change of residence". This broad definition, of course, would include a move across the street or across a city. Our concern is with movement between nations, not with internal migration within nations, although such movements often exceed international movements in volume. Today, the motives of people who move short distances are very similar to those of international migrants.
Students of human migration speak of "push" and "pull" factors, which influence an individual’s decision to move from one place to another. Push factors are associated with the place of origin. A push factor can be as simple and mild a matter as difficulty in finding a suitable job, or as traumatic as war, or severe famine. Obviously, refugees who leave their homes with guns pointed at their heads are motivated almost entirely by push factors (although pull factors do influence their choice of destination).
Pull factors are those associated with the place of destination. Most of these are economic, such as better job opportunities or the availability of good land to farm. The latter was an important factor in attracting settlers to the United States during the 19th century. In general, pull factors add up to an apparently better chance between several attractive potential destinations, the deciding factor might be a non-economic consideration such as the presence of relative, friends, or at least fellow countrymen already established in the new place who are Willing to help the newcomers settle in. Considerations of this sort lead to the development of migration flow.
Besides push and pull factors, there are what the sociologists call" intervening obstacles". Even if push and/or pull factors are very p they still may be outweighed by intervening obstacles, such as the distance of the move, the trouble and cost of moving, the difficulty of entering the new country, and the problems likely to be encountered on arrival.
The decision to move is also influenced by" personal factors" of the potential migrant. The same push- pull factors and obstacles operate differently on different people, sometimes because they are at different stages of their lives, or just because of their varying abilities and personalities. The prospect of packing up everything and moving to a new and perhaps very strange environment may appear interesting and challenging to an unmarried young man and appallingly difficult to a slightly older man with a wife and small kids. Similarly, the need to learn a new language and customs may excite one person and frighten another.
Regardless of why people move, migration of large numbers of people causes conflict. The United States and other western countries have experienced adjustment problems with each new wave of immigrants. The newest arrivals are usually given the lowest-paid jobs and are resented by native people who may have to compete with them for those jobs. It has usually taken several decades for each group to be accepted into the mainstream of society in the host country.

Which of the following is not true

A．Migration of large numbers of people may cause conflict.

B．The newest arrivals can hardly get good jobs.

C．Native people often resent newest arrivals because they cannot communicate easily with the latter.

D．Usually it has taken several decades for each group of newest arrivals to be accepted into the main-stream of society in the host country.

瞳孔的大小( )

A．与睫状肌舒缩有关

B．远视时瞳孔缩小

C．受中脑内动眼神经核控制

D．弱光时瞳孔开大

E．瞳孔开大与副交感神经有关