今天前程百利小编为大家分享的是托福听力的背景学习。备考托福听力就要把听力文本吃透分析彻底。这样不仅能积累背景材料，还能把听力的专业词汇积累起来一块背诵，为托福听力打下坚实的基础。下面跟小编一起看一下贝壳的形状与安全有什么关系吧?
Analysis of clamshell and screw-shaped shells reveals the structures withstand much greater forces than would a simple sphere or cylinder. Cynthia Graber reports
Scientists have been looking to nature for inspiration for materials with useful properties. Insect exoskeletons and shark skin are examples of materials that exhibit strength, durability, and less wind and water drag.
They’re also looking at natural construction that could inform our own design projects. In that arena, researchers recently focused on the shape and structure of seashells. In a new study, they report on the properties of two types of shells collected from a sea shore in southern India: a bivalve with a typical clamshell-style shell, and a screw-type shell belonging to a turbinate.
The scientists performed a detailed analysis of the structures and the ways in which they respond to stresses at various locations.
They determined that the bivalve distributes force along the outer edge of the shell to protect the soft body inside. The screw-shaped shell keeps force directed at large rings while the soft body stays within the smaller rings.
The two shell shapes can survive loads nearly double that which could be withstood by a simple sphere or cylinder. So if you wind up driving a shell-shaped car someday, it’ll be both stylish and designed to protect the soft bodies inside.
疑难词汇：
Clamshell n. 蛤壳状挖泥器;蛤壳
Cylinder n. 圆筒;汽缸;[数] 柱面;圆柱状物
Property n. 性质，性能;财产;所有权
Exoskeleton n. [昆] 外骨骼
Durability n. 耐久性;坚固;耐用年限
Inform vt. 通知;告诉;报告vi. 告发;告密
Bivalve n. 双壳贝;[无脊椎] 双壳类动物adj. 双壳的;两瓣的
Turbinate adj. 陀螺状的n. 鼻甲骨;螺旋形介壳
Stylish adj. 时髦的;现代风格的;潇洒的
长难句解析：
1. Insect exoskeletons and shark skin are examples of materials that exhibit strength, durability, and less wind and water drag.
难句类型：
That引导的定语从句
句子主干：
Insect exoskeletons and shark skin are examples of materials
难句拆分：
that exhibit strength, durability, and less wind and water drag，That引导的定语从句。
2. They determined that the bivalve distributes force along the outer edge of the shell to protect the soft body inside.
难句类型：
That引导的宾语从句
句子主干：
They determined that
难句拆分：
that the bivalve distributes force along the outer edge of the shell to protect the soft body inside，that引导的宾语从句，作determined的宾语，to protect the soft body inside，作目的状语，along the outer edge of the shell，介词短语作outer edge的定语。
3. The two shell shapes can survive loads nearly double that which could be withstood by a simple sphere or cylinder.
难句类型：
Which引导的定语从句
句子主干：
The two shell shapes can survive loads
难句拆分：
That在这句话中是代词;which could be withstood by a simple sphere or cylinder，which引导的定语从句修饰loads。
文本结构特点：
本篇文章主要讲的是贝壳的形状和自身的身体状况是有关系的。研究表明贝壳的的形状促使它承受巨大的负担。
好了，以上就是前程百利小编为大家整理的备考托福听力背景材料以及专业词汇的学习。大家学会了吗?希望能在备考托福的路上助大家一臂之力。预祝大家取得好成绩。
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