题干

下列有关种群特征的叙述,正确的是(     )

A:性比率是所有种群都具有的特征

B:自然增长率主要由出生率决定

C:—个城市的人口数量可以反映其人口密度

D:年龄结构稳定的人群保持零增长

上一题 下一题 0.0难度 选择题 更新时间:2019-12-15 01:15:09

答案(点此获取答案解析)

C

同类题2

根据短文内容及所给首字母提示写出所缺单词,使短文意思完整,每空一词。

    When you have dinner, you follow table manners. When you have a l____ , you obey the rules in the classroom. But have you ever thought about needing to m____ your manners in the digital(数码的) world when you use phones, e-mails and social media, like QQ, WeChat, etc?

    As new research by Oxford University noted, "It's just important to treat people with respect online as it is in real life." The study came up with some rules of good manners to live by in the digital age. Their first a____ is not "over-sharing" on social media, which means not posting every detail about your life online, because some of us are not creative e____ to always show off our thoughts and lives on social media.  The manners also i____ not looking through others' phones and not gossiping(说闲话) about others over messages, e____ when you choose "reply all" to send a message to a group of people.

    Although gossip is not h____ chat that can make conversations exciting, it can also be a way to spread something untrue about other people. Gossip can be even stronger on social media than in real life, so it's b____ not to gossip.

    Moreover, when you have bad news for someone, do not leave text messages on social media, chat with him or her by c____ personal messages.

    Nowadays, technology has o____ us different ways to contact others. It is important to remember how to behave toward others online.