原型模型是增量模型的另一种形式，用于需求分析阶段的模型是（）。A．探索型原型 B．实

脂酰辅酶A进入线粒体的载体是

A．丙酮酸

B．鱼藤酮

C．氨甲磷酸

D．乙酰谷氨酸

E．肉碱

Today’s lecture is about the mass (1) of the world’s population. There are two major (2) why people are moving to cities. The first reason is (3) . People are moving to the cities because that’s where they can find (4) and earn money. The second reason for the move to cities has to do with (5) of life issues: comfort and (6) . Cities often offer better (7) . And then for many, city life is just more (8) . An interesting consequence of urbanization is that the average (9) of people in the countryside is increasing, while that of the cities is (10) .
Three key (11) can be identified in our cities. First of all, they’re getting bigger. Most cities are bigger now than ever before. Cities are also changing shape. They’re getting (12) , because land is getting more and more expensive. (13) have become a symbol of modern cities.
Cities are also changing shape in other ways. The (14) Model and the (15) Nuclei Model are probably more typical of the cities we know today. They show the urban (16) that’s occurring in contemporary cities.
The third change is that our cities are breaking up into (17) communities, often by (18) group or (19) level. This often means that people stay within their community and do not come into contact with others from different (20) .

废旧的电器、电池可直接扔掉。（）

A.正确

B.错误

函数f(x)=x³-3x²-9x+a的图像经过四个象限的充要条件______．

A．a＞0
B．a＜0
C．-10＜a＜30
D．-5＜a＜27

甲省A市中级人民法院与乙省B市中级人民法院之间因执行案件的管辖权发生争议，双方协商无法达成一致，此时（）。