下面图表的横轴表示城市人口规模，纵轴表示城市的效益与成本，根据城市经济的各种收益和成本之间的关系，我们可以考察各种城市规模的适宜情况。
P1：城市功能基本形成点，P2：城市的最小门槛规模；P3：城市最低成本规模；P8：城市最大人口规模。
关于城市人均产出与城市边际投入产出的说法正确的是（）。
A．城市人均产出额先随人口规模的增加而增加，达到最高值时，义逐渐减少
B．城市边际投入额随人口规模的增加，先递增，达到最高值后开始递减
C．P5是城市边际投入产出最高点
D．P4是人均效益最高点
参考答案：A
解析：
刚开始城市经济效益的增速大于人口规模的增长，相应的城市人均产出额增加，到P6点时城市经济效益达到最大规模，P6点后城市经济规模开始减少，故城市人均产出额随人口规模增加而减少。选项A正确。
| 阅读理解。 | ||
to explaining why he is dressed in a stylish grey and purple sweater. "He was hanging around looking for somebody to love him I tried to cheer him up-he seemed happy to see me," said the photographer Chris Michael. One of the four photos of the pug on Flickr is titled "Tough day for Mr. Newman" and with some other words as follows:"Despite his cool clothes, the girls just aren't interested in him any more." Dozens of people on the site said they had been touched by the dog's pitiful expressions. "I come back to see this photo every now and then because it's too cute, so does my daughter. In fact, my family all are touched," wrote one of the pedestrians who had seen the photo. Another viewer said that she had been so moved as to buy a pug of her own after seeing the photos. Mr. Newman may have won the hearts of internet users but he is unlikely to be more famous than a cat competitor Keyboard Cat, the musical pet who has become a star on YouTube. | ||
| 1. The little pug waited by the road probably because | ||
[ ] | ||
| A. it was abandoned by its owner. B. it was left behind by his owner C. it was trapped by a passer-by. D. it couldn't find the way home. | ||
| 2. We can infer from the passage that the photographer Chris Michael _____. | ||
[ ] | ||
| A. knew much about the owner of the dog B. helped to find the owner of the pug C. took great interest in its colorful sweater D. tried to amuse the pug in some ways | ||
| 3. The writer used the underlined sentence from the website to _____. | ||
[ ] | ||
| A. add some humor to the passage B. describe the pug's loveliness C. help the dog owner recognize it D. inform girls to adopt the dog | ||
| 4. What would be discussed next according to the text? | ||
[ ] | ||
| A. Description of another dog B. The pug's recent situation C. Some details about the keyboard cat D. Pet owners' responsibility |
