首页
登录
职称英语
[originaltext] Many egg-laying animals merely lay their eggs and leave. Turt
[originaltext] Many egg-laying animals merely lay their eggs and leave. Turt
游客
2023-07-11
14
管理
问题
Many egg-laying animals merely lay their eggs and leave. Turtles, for instance, and horseshoe crabs, the eggs hatched and the little ones are their own. The current theory about birds is the earliest birds did just that when they were cold-blooded creatures living in warm places. However, when they became warm-blooded creatures living in cold places, they had to remain on the eggs to keep them warm. For this, they needed a place--a nest. Very likely, the first nest was just a primitive hole scraped in the ground. Even now many species still lay eggs in this sort of crude nest. Primitive nests found on the ground were fine for some birds, but others began to elevate their nests in branches, perhaps to avoid predators. These early elevated nests were probably loose platforms of sticks and dried leaves. The type is still built by some birds today. The latest development in nest, the most recent vision, so to speak, is the cup-shaped nest. This is the one we regard today as the typical bird’s nest, you know, like a robin’s nest.
选项
A、Their flying ability improved greatly.
B、They became warm-blooded.
C、They began to lay eggs.
D、They changed their migration patterns.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2827661.html
相关试题推荐
[originaltext]Thetwentiethcenturyhasbroughtwithitmanyadvances.(32)
[originaltext]Caroleisateenagegirl.Shethinkssheisabittoofat,or
[originaltext]Caroleisateenagegirl.Shethinkssheisabittoofat,or
[originaltext]W:Noluckthen,John?M:I’mafraidnot,ma’am.Notyet,anyhow.
[originaltext]W:Noluckthen,John?M:I’mafraidnot,ma’am.Notyet,anyhow.
[originaltext]W:Whatdoyouplantoorder?M:Ithink,I’llhaveasaladanda
[originaltext]W:Whatdoyouplantoorder?M:Ithink,I’llhaveasaladanda
[originaltext]Sportscanhelpyoukeepfitandgetintouchwithnature.Ho
[originaltext]Sportscanhelpyoukeepfitandgetintouchwithnature.Ho
[originaltext]Sportscanhelpyoukeepfitandgetintouchwithnature.Ho
随机试题
[audioFiles]audio_eufm_j68_001(20082)[/audioFiles]A、Shehopesthefruitsarein
[originaltext]YoucouldsaythatJosephCornellbecameanartistbecauseof
Inviewofthepotentialsideeffects,pregnantwomenareadvised______(不要服用这种药)
结合社会现象,谈谈人本主义心理学在社会中的应用。
下列各项中,哪种药物可治疗毒性弥漫性甲状腺肿患者的部分症状,但不降低甲状腺合成、
水平角观测方法有测回法和方向观测法,其观测限差有所不同,方向观测法的限差有(
穿墙套管末屏接地处有放电声音及电火花,说明()。穿墙套管末屏放电$;
2010年,天津市全市生产总值突破9000亿元。据初步核算,并经国家统计局评估审
抵押权与其担保的债权同时存在,债权消失的,抵押权也消失。()
受理执业医师注册申请的机构是A.户籍所在地卫生行政部门 B.所在地县级以上卫生
最新回复
(
0
)