已知方程  $a{x}^2+bx+cy=0$（ $a\ne 0$ ， b 、 c 为常数），请你通过变形把它写成你所熟悉的一个函数表达式的形式．则函数表达式为____，成立的条件是____，是　____函数．

环境人口容量是指一个地区或一个国家能持续供养的人口数量。1850年，清朝的人口为4.3亿。当时的学者汪士铎惊呼：“人多之害，山顶已植黍稷，江中已有洲田，川中已辟老林，苗洞已开深菁，犹不足养……”。而今天的中国，不但养活了13亿人，人们的生活水平比那个时代还提高了许多。回答14～15题。
【小题1】材料表明影响环境人口容量的重要因素是

A．地区对外开放程度

B．人口的生活与文化消费水平

C．科技发展水平

D．蕴藏的资源数量

【小题2】随着人口不断增加，我国必须进行人口合理容量的估计，其主要意义在于

根据短文内容，选择正确答案。
D
    John sent for a doctor because his wife was ill. He called the doctor and made sure they would meet at five. He arrived at the doctor's at twenty to five. He thought. “It s a little bit earlier. I'll wait for a moment. It's good to keep the time. ”
    Then he stopped his car in front of the doctor's. He looked around and saw a noisy square not far from here. He went there and sat down on a chair to enjoy the last light of afternoon sun and make himself quiet. He saw some children playing and some women talking to each other happily.
    Suddenly he heard a girl crying. He came up to her and asked some questions. Then he knew she got lost. John tried to find out her address and took her home. The girl's parents were very thankful.
    Then John hurried to the doctor's. The doctor said angrily when he saw him “You're late. Why did you keep me waiting for 20 minutes?" John said nothing but one word "Sorry!”

5月份，某市出现首例入性中东呼吸综合征确诊病例．中东呼吸综合征是一种新型冠状病毒引起的呼吸道传染病．下列相关叙述错误的是（  ）

读图，完成以下问题。