四级课程经典
零基础适用HOT
去试听
四级1对1
定制化
核心词 背词计划
0元
听力 蜕变必备
0元
阅读 冲刺200+
0元
写作 高分模板带练
0元
送历年真题
免费
模考 水平测试
热门
1V1速成方案VIP
The pressure inside the animal may increase by 10 times. This pressure change greatly stretches the fibers, enabling much energy to be stored.
This energy is then transferred to the tail, and the shark is off. The rest of the story is predictable.
Dolphin Has Speed Record
Another fast marine animal is the dolphin. This seagoing mammal has been clocked at speeds of 32 kilometers (20 miles) an hour. Biologists studying the dolphin have discovered that, like the shark, the animal’s efficient locomotion can be traced to its skin. A dolphin’s skin is made up in such a way that it offers very little resistance to the water flowing over it. Normally when a fish or other object moves slowly through the water, the water flows smoothly past the body. This smooth flow is known as laminar flow. However, at faster speeds the water becomes more turbulent along the moving fish. This turbulence muses friction and slows the fish down.
In a dolphin the skin is so flexible that it bends and yields to the waviness of the water. The waves, in effect, become tucked into the skin’s folds. This allows the rest of the water to move smoothly by in a laminar flow. Where other animals would be slowed by turbulent water at rapid speeds, the dolphin can race through the water at record breaking speeds.
Other Animals Less Efficient
Not all animals move as efficiently as sharks and dolphins. Perhaps the greatest loser in locomotion efficiency is the slug. The slug, which looks like a snail without a shell, lays down a slimy trail over which it crawls. It uses so much energy producing the slimy mucus and crawling over it that a mouse traveling the same distance uses only one twelfth as much energy.
Scientists say that because of the slug’s inefficient use of energy, its lifestyle must be restricted. That is, the animals are forced to confine themselves to small areas for obtaining food and finding proper living conditions. Have humans ever been faced with this kind of problem?
1.According to the passage, a shark can use movement to do something except____________.
[A]to find food
[B]to avoid being chased by its enemies
[C]to find a new place to live
[D]to show its braveness
2.Examples of automobiles, rockets and submarines are used to show that _______________.
[A]humans are the most clever living creatures in the world
[B]human inventions enable us to travel in almost any kind of environment
[C]humans are very successful in inventing transportation tools
[D]humans can’t move like other animals in any circumstances
3.What is the key to the shark’s swift locomotion in water?
[A]The skin. [B]The tail. [C]The muscle. [D]The jaw.
4.According to the Duke University scientists, when does the shark stretch its collagen fibers to the greatest extent?
[A]When moving its tail rapidly.
[B]When finding its preys.
[C]When staying without any movement.
[D]When bending its body in swimming.
5.Why is the area just under the shark’s collagen fibers similar to a belted radial tire?
[A]Because it is also full of blood pressure.
[B]Because it is also filled of air pressure.
[C]Because it is also inflated by pressure.
[D]Because it also can be used again and again.
新东方英语四级好课免费听↓↓↓
课程名称 | 课程亮点 | 试听 |
【小班课】英语四六级零基础无忧计划 | 1V1答疑 | 免费试听 |
【零基础】四六级全科专项突破 | 单项全面进阶 | 免费试听 |
【阅读】四六级阅读高分技巧 | 双师精讲阅读 | 免费试听 |
【写作】四六级写作万能模板 | 双师精讲写作 | 免费试听 |
【听力】四六级听力高分技巧 | 双师精讲听力 | 免费试听 |
【寒假班】英语四六级全程班 | 考前冲分快准狠 | 免费试听 |
了解更多四六级课程 |
资料下载
新东方四级词汇乱序版电子资料
发布时间:2020-04-15关注四六级小助手服务号
回复【过级词汇】获取
英语口语8000句电子书籍
发布时间:2020-04-15关注四六级小助手服务号
回复【过级词汇】获取
新东方在线[四六级王牌团队]典藏笔记(...
发布时间:2019-10-25关注四六级小助手服务号
回复【典藏笔记】获取
英语四级过级备考资料:经验+计划+语法
发布时间:2019-10-25关注四六级小助手服务号
回复【过级经验】获取
英语四级阅读讲义+长难句+翻译
发布时间:2019-10-25关注四六级小助手服务号
回复【阅读礼包】获取
英语四级写作模板|范文|句型|讲义
发布时间:2019-10-25关注四六级小助手服务号
回复【写作指导】获取
新东方·大学英语四级听力特训附音频
发布时间:2019-10-25关注四六级小助手服务号
回复【听力礼包】获取
英语四级口语考试练习题目【word版】
发布时间:2019-10-25关注四六级小助手服务号
回复【口语提升】获取
俞敏洪词根词缀记忆法
发布时间:2019-10-25关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号回复【典藏笔记】获取
关注新东方四级服务号,
获取学习资料
推荐阅读
更多>>在英语四级备考的过程中,英语四级阅读是对学生深度理解、分析和应用英文文本的考量,如何高效阅读英语文章,下面是小编给大家分享的“2024年6月大学英语四级阅读练习及解析(1)”,供考生阅读练习。
来源 : 网络 2024-04-17 08:08:00 关键字 : 英语四级阅读
在英语四级备考的过程中,英语四级阅读是对学生深度理解、分析和应用英文文本的考量,如何高效阅读英语文章,下面是小编给大家分享的“2024年6月大学英语四级阅读练习及解析(2)”,供考生阅读练习。
来源 : 网络 2024-04-17 08:08:00 关键字 : 英语四级阅读
在英语四级备考的过程中,英语四级阅读是对学生深度理解、分析和应用英文文本的考量,如何高效阅读英语文章,下面是小编给大家分享的“2024年6月大学英语四级阅读练习及解析(3)”,供考生阅读练习。
来源 : 网络 2024-04-17 08:08:00 关键字 : 英语四级阅读
在英语四级备考的过程中,英语四级阅读是对学生深度理解、分析和应用英文文本的考量,如何高效阅读英语文章,下面是小编给大家分享的“2024年6月大学英语四级阅读练习及解析(4)”,供考生阅读练习。
来源 : 网络 2024-04-17 08:08:00 关键字 : 英语四级阅读
在英语四级备考的过程中,英语四级阅读是对学生深度理解、分析和应用英文文本的考量,如何高效阅读英语文章,下面是小编给大家分享的“2024年6月大学英语四级阅读练习及解析(5)”,供考生阅读练习。
来源 : 网络 2024-04-17 08:08:00 关键字 : 英语四级阅读
专项提升公开课
更多>>110小时干货精讲,包邮3斤礼盒,无忧换课
价格 : ¥269元
限报人数:1000人
名师解析,新学期备考攻略
价格 : ¥0元
限报人数:1000人
大咖云集 名师授课
价格 : ¥149元
限报人数:1000人
告别听力‘小聋瞎’
价格 : ¥0元
限报人数:10000人
资料下载
更多>>关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号
回复【过级词汇】获取
关注四六级小助手服务号
回复【典藏笔记】获取
关注四六级小助手服务号
回复【过级经验】获取
关注四六级小助手服务号
回复【阅读礼包】获取
关注四六级小助手服务号
回复【写作指导】获取
关注四六级小助手服务号
回复【听力礼包】获取
关注四六级小助手服务号
回复【口语提升】获取
关注四六级小助手服务号
回复【过级词汇】获取
阅读排行榜
相关内容