物种形成方式可分为异域性物种形成、邻域性物种形成以及__________。-湖北继续教育网网校

首页

普通专升本

成人高考

学位英语

在线刷题

最近学习

最近学习课程

最强大脑 · 3天挑战极限记...

副标题副标题副标题副
最强大脑 · 3天挑战极限记...

副标题副标题副标题副

您现在位置：模拟考场> 湖北成人高考> 专升本> 生态学基础> 浏览试题

[填空题]

物种形成方式可分为异域性物种形成、邻域性物种形成以及__________。

收藏查看答案

相关题目

热门试题

1. 消费信贷的变动趋势与储蓄的变动趋势的关系是（）
2. 26.与企业持有现金的支付动机有关的经济活动有
3. 试述道教对中国文化的影响。
4. 简述常作为麻醉前给药的M受体阻断药有哪些?何者为优?为什么?
5. 3.Friction is a force which opposes motion. Much of the energy supplied to a complicated machine with many moving parts is wasted in overcoming this opposition. The energy is converted into useless heat. The amount thus lost can be considerably reduced and the life of the machine prolonged by careful lubrication. This reduction improves the efficiency of the machine. Another way in which friction is reduced is to substitute roller or ball bearings for the earlier type of bearing, in which the surfaces in contact move by sliding. Bearings of these later types are used very extensively in many kinds of modern machinery.It must not be assumed, however, that friction is always a disadvantage. In many instances it is highly important. Belts are often used in conveying power from one machine to another. In the absence of friction, this could not be done. The driving wheel would not run the belt, neither would the belt run the wheel to driver. Without friction, then, belted machinery could not be used. Again in the case of all motor vehicles, friction is essential in the operation of the brake. Were there no friction, there could be no brake. But even this illustration does not give an adequate picture of the importance of friction. The vehicle could not even be started if it were not for the friction exerted between the tires and the road. Nails hold in wood, and screws hold in either wood or metal by reason of friction, without which they would be useless. Walking is difficult enough on an icy pavement, but it would be wholly impossible if there were no friction at all between the shoe and the pavement.(5分)3.1Friction arises when____.(1分)A. an opposing force of motion existsB. the energy is wastedC. everything is motionlessD. a complicated machine is supplied with energy

热门试卷