1.
While both of these have their advantages and disadvantages, a frame-based site is usually easier to update.
这两种布局方法各有自己的优缺点，框架网站通常更容易下载。
2.
Since his early 20s, he has suffered from amyotrophic lateral sclerosis (ALS), a progressive deterioration of the central nervous system that usually causes death within three or four years.
因为在20年代早期他患上了肌萎缩性脊髓侧索硬化症（ALS），中枢神经系统逐渐变坏以至于通常会在三至四年内导致死亡。
3.
In front of the A/D converter in an analog conversion system is usually located a sample-and-hold circuit.
在模拟量转换系统中在模/数转换器的前端通常都会有一个采样-保持电路。
4.
A person whose blood type is AB usually has a double character.
血型是AB型的人通常会有双重性格。
5.
In a steam engine, hot steam, usually supplied by a boiler, expands under pressure, and part of the heat energy is converted into work.
在蒸汽机内，通常由锅炉供应的热蒸汽在压力下膨胀，部分热能转化为功。
6.
A vehicle consisting of a frame mounted over a single wheel and usually propelled by pedals.
独轮脚踏车一种由装有单轮的机架构成的车辆，通常由脚蹬推动
7.
Side head: Words in the form of headings. But run on at the commencement of a paragraph; they are usually followed by a one-em rule.
边标题:标题字词，排于每段开始之前，用一长划(破折号)隔开后，内文接续排下支的方式。
8.
Ad(s):Shot for advertisement, usually referred to newspaper A.D.magazine advertising. An abbreviation commonly used in America.
广告:ad是广告的简写。通常指报纸及杂志上的广告，在美国较常用。
9.
AD: Latin, short for anno Domini, meaning in the year of our Lord. Usually set in small caps A.D.before the figures (e.g. AD 250).
公元:AD是拉丁anno Domini的缩写;是主历年度的意思。排英文时，应用小型大写，放于年份之前。
10.
Refractories are provided in a variety of physical forms, such as shapes AAD monoliths. Shapes are usually bricks.
耐火材料可以制成各种物理形态，如各种型料和整体料。型料通常为砖形。
小测验：选择正确的单词
词汇听力：
