皮皮学,免费搜题
登录
logo - 刷刷题
搜题
【单选题】
Naturalists and casual observers alike have been struck by the special relationship between squirrels and acorns (the seeds of oak trees). Ecologists, though, cannot observe These energetic mammals scurrying up and down oak trees and eating and burying acorns without wondering about their complex relationship with trees. Are squirrels dispersers (5) and planters of oak forests or pesky seed predators? The answer is not simple. Squirrels may devour many acorns, but by storing and failing to recover up to 74 percent of them (as they do when seeds are abundant), these arboreal o/rodents can also aid regeneration and dispersal of the oaks. Their destructive powers are well documented. According to one report, squirrels (10) destroyed tens of thousands of fallen acorns from an oak stand on the University of Indiana campus. A professor there estimated that each of the large while oaks had. Produced between two and eight thousand acorns, but within weeks of seed maturity, Hardly an intact acorn could be found among the fallen leaves. Deer, turkey, wild pigs, and bears also feed heavily on acorns, but do not store them, (15) And are therefore of no benefit to the trees. Flying squirrels, chipmunks, and mice are Also unlikely to promote tree dispersal---whose behavior. of caching (hiding) acorns below The leaf litter often promotes successful germination of acorns---and perhaps blue jays, Important long-distance dispersers, seem to help oaks spread and reproduce. Among squirrels, though, there is a particularly puzzling behavior. pattern. Squirrels (20) pry off the caps of acorns, bite through the shells to get at the nutritious inner kernels, and then discard them half-eaten. The ground under towing oaks is often littered with thousands of half-eaten acorns, each one only bitten from the top. Why would any animal waste so much time and energy and risk exposure to such predators as red-tail hawks only to leave a large part of each acorn uneaten? While research is not conclusive at this point, (25) one thing that is certain is that squirrels do hide some of the uneaten portions, and these acorn halves, many of which contain the seeds, may later germinate. What does the passage mainly discuss?
A.
The ecology of oak trees
B.
Factors that determine the feeding habits of Squirrels
C.
Various species of animals that promote the dispersal of tree seeds
D.
The relationship between squirrels and oak trees
手机使用
分享
复制链接
新浪微博
分享QQ
微信扫一扫
微信内点击右上角“…”即可分享
反馈
参考答案:
举一反三
【单选题】胎盘合成甾体激素错误的是()
A.
主要有孕激素的雌激素
B.
孕二醇于妊娠足月24小时尿液中排出量约5mg
C.
雌激素由胎儿-胎盘单位产生
D.
胎儿肾上腺及肝产生雌激素前身物质,是胎盘合成雌三醇的主要来源
E.
测孕妇血、尿或羊水中的雌三醇值,是了解胎儿在宫内状况的好方法
【单选题】Which is not belong to unit combination instrument?( )
A.
electric unit combination instrument
B.
pneumatic unit combination instrument
C.
base type instrument
D.
others
【简答题】MCS-51系列单片机常用的复位方法有几种?画电路图。
【多选题】互联网金融的特点是
A.
成本低、效率高
B.
覆盖广、发展快
C.
管理弱、风险大
D.
数据多、分析强
【单选题】8 在旅游事故中去世的旅游者,其遗物应由( )共同清点。
A.
我方人员
B.
死者同行人员
C.
所属国驻华使、领馆人员
D.
以上三者
【单选题】( ) is a minimal unit which is formally composed of meaningless linguistic symbols at the lower level of the language
A.
Phoneme
B.
Stress
C.
Tempo
D.
Morpheme
【单选题】胎盘合成甾体激素错误的是
A.
主要有孕激素和雌激素
B.
孕二醇于妊娠足月24小时尿液中排出量约5mg
C.
雌激素由胎儿—胎盘单位产生
D.
胎儿肾上腺及肝产生雌激素前身物质,是胎盘合成雌三醇的主要来源
E.
测孕妇血、尿或羊水中的雌三醇值,是了解胎儿在宫内状况的好方法
【单选题】According to the last paragraph, which one is true?
A.
Homework will be handed in via electronic mail system.
B.
Homework will be not be assigned.
C.
Students never take examinations.
D.
Students get the score after a long time.
【多选题】对于胎盘合成的甾体类激素,下列哪些是恰当的()
A.
主要有孕激素和雌激素
B.
孕激素于妊娠末期24小时尿中排出量<5mg
C.
雌激素由胎儿胎盘单位产生
D.
胎儿肾上腺及肝脏产生雌激素前身物质,是胎盘合成雌三醇的主要来源
E.
测定孕妇血、尿或羊水中的雌三醇值,是为了了解胎儿在宫内的状况
【判断题】企业采用向上延伸策略推出高档产品会提升企业的形象,故从企业的推销员、经销商到市场上的顾客都会欢迎并接受企业的高档产品。
A.
正确
B.
错误
相关题目:
参考解析:
知识点:
题目纠错 0
发布
创建自己的小题库 - 刷刷题