首页
登录
职称英语
[originaltext] Many egglaying animals merely lay their eggs and leave. With
[originaltext] Many egglaying animals merely lay their eggs and leave. With
游客
2023-07-12
77
管理
问题
Many egglaying animals merely lay their eggs and leave. With turtles for instance, the eggs hatch on their own. The current theory about birds is that the earliest birds did just that, when they were coldblooded creatures living in warm places. However when they became warmblooded creatures living in cold places they had to remain on top of the eggs to keep them warm. This process we call incubation. For this they needed a place, a nest very likely the first nests were just primitive depressions scraped into the ground. Even now many species still lay eggs in this sort of crude nest. In fact, every spring a mother killdeer lays her eggs in scene pebbles along the edged the parking lot just outside this building. Primitive nests on the ground were fine for some birds but others began to elevate their nests onto Branches, perhaps to avoid predators. These early elevated nests were probably loose platforms of sticks and twigs, the types still built by ospreys and mostarians today. The latest evolutionary development in nests the most re cent version, so to speak, is the cupshaped nest. This is the one we regard today as the typical bird’s nest, you know, like a robin’s nest.
选项
A、How birds’ nests have evolved.
B、Why some birds’ nests am considered primitive.
C、How birds learn to build nests.
D、Why birds lay eggs.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2830014.html
相关试题推荐
[originaltext]Arecentfilm,TheCodsMustBeCrazy,describedthesocialc
[originaltext]Arecentfilm,TheCodsMustBeCrazy,describedthesocialc
[originaltext]TheCivilWarcameaboutasaresultofmanydifferencesbetw
[originaltext]ColumbussailedfromSpaininSeptember1492,lookingforgold.
[originaltext]ColumbussailedfromSpaininSeptember1492,lookingforgold.
[originaltext]M:Hello.Ineedtotalkwithsomeoneaboutmydriver’slicense.
[originaltext]M:Hello.Ineedtotalkwithsomeoneaboutmydriver’slicense.
[originaltext]M:Hello.Ineedtotalkwithsomeoneaboutmydriver’slicense.
[originaltext]M:Excuseme.Haveyoubeenwaitinglong?W:Abouttenminutes.M
[originaltext]M:Linda,whydoyouneedmynotes?IrememberseeingyouinProf
随机试题
Ifaisincreasedby25%andbisdecreasedby25%,theresultingnumberswillb
RecentlyasociologistfromtheUniversityofNewHampshire,MurrayStraus,
发挥着作用function
“譬如为山,未成一篑,止,吾止也;譬如平地,虽复一篑,进,吾往也”这段话所用的逻
给水泵站内经常启闭且大于及等于DN300mm的阀门不宜采用( )。A.电动
一般而言,下列符合教育支出特点的有()。A.费用弹性较大 B.费用逐年
析词:指为了表达的特殊需要,临时把某个词语拆开使用的修辞手法。 下列属于析词的
A.双端固定桥 B.单端固定桥 C.局部义齿 D.种植义齿 E.暂不修复
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
(2019年真题)按照国际通用的预警信号颜色表示,安全状况为“受到事故的严重威胁
最新回复
(
0
)