题干

某岛屿上生活着一种动物,该动物个体从出生到性成熟需耍6个月。右图为某年该动物种群 在不同月份的年龄结构(每月最后一天统计种 群各年龄组成个体数)。关于该种群的叙述,正确的是

A:9月份种群出生率一定不是0

B:这段时间内,该种群的数量一定保持相对稳定

C:该种群数量受气候、食物、行为调节等外源性因素的影响

D:神群密度越大,传染病对该种群数量增松的抑制作用也越强

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答案(点此获取答案解析)

D

同类题1

阅读下面短文,掌握其大意,然后从每题所给的A、B、C、D四个选项中选出最佳答案

    Have you heard of STEM education? STEM 1 Science, Technology, Engineering and Mathematics. It means students can learn these 2subjects in one class. And they work on many projects to practice 3 they learn STEM education is very 4 in the US.

    Now more than 600 5 middle schools bring in STEM education, according to the paper, en. Beijing, Yuying School is one of them.

    The school 6 the course in May. It invited college teachers to teach more than 80 students programming, robotics and other interdisciplinary(跨学科}的) knowledge.

    The teaching style is quite 7, Once teachers finish teaching basie knowledge, studentes will practice it 8. For example, after learning about electrie circuits(电路),students are required to design one that could control three lights 9.They have many projects to improve their hands-on 10 as well. Once, they had a "smart home" model design project. All the students competed to design a 11 model and make it "smart" .Liu Tianyou, 12, with 12 teammates, used computer programs and sensors to finish it. "If you open the door of the house, the lights will 13 automatically, "he said. Their work won the third prize.

    The class, develops students' creativity as well. 14 Learning mechanies and programming in the class, Zhao Hngyi, 14, made a Lego robot himself in eight 15.From assembling(组装)to testing he finished it on his own. The robot can catch things and walk on certain tracks under orders. " It's cool to make my idea come to life," he said.