比较状语从句，比较状语从句是对不同事物或人物进行比较说明，主要运用于形容词和副词的原级、比较级及最高级的句子之中。引导比较状语从句的连词主要是as和than，通过其他手段与它们结合便形成了各种不同的比较。
原级：as…as(和……一样), not so(as) …as…(和……不一样)
比较级：more…than; less…than
常用引导词：as(同级比较), than(不同程度的比较)
特殊引导词：the more…the more… ; no…more than
1.同级比较，表示人或事物的某一属性在比较之下程度一致。
(1)“as+形容词/副词+as”表示“和……一样”，第一个as为副词，后一个as为连词。
《剑桥雅思真题8》Test 4 Passage 3
Collecting ants can be as simple as picking up stray ones.
收集蚂蚁就像捡起迷路的蚂蚁一样简单。
《剑桥雅思真题9》Test 2 Passage 2
Teams of British and French astronomers set out on expeditions to places as diverse as India and Siberia.
由英国和法国天文学家组成的团队开始了对印度和西伯利亚等不同地区的考察。
《剑桥雅思真题10》Test 3 Passage 3
This must have been as difficult for them as landing on the moon is for us today.
对他们来说，这一定和我们今天登上月球一样困难。
《剑桥雅思真题11》Test 3 Passage 1
The Byzantines were as secretive as the Chinese.
拜占庭人和中国人一样神秘。
《剑桥雅思真题13》Test 1 Passage 3
A computer might create something as original and subtle as our best artists.
电脑可能会像我们最好的艺术家一样，创造出一些原创而微妙的东西。
(2)“as+many/much/形容词+名词+as”表示“……和……一样”，前一个as为副词，后一个as为连词。其中many/much不能和后面的名词分开。
《剑桥雅思真题5》Test 2 Listening Section 2
They could never do as many jobs as my neighbour.
他们不可能做像我邻居那样多的工作。
《剑桥雅思真题7》Test 1 Passage 2
At the height of the Roman Empire, nine major systems, with an innovative layout of pipes and well-built sewers, supplied the occupants of Rome with as much water per person as is provided in many parts of the industrial world today.
在罗马帝国的鼎盛时期，九个主要的系统，以创新的管道布局和建造精良的下水道系统，为罗马的居民提供了今天工业世界许多地区所提供的人均水量。
《剑桥雅思真题8》Test A Section 3
Selling ‘snake oil' was almost as risky a business as cattle stealing.
卖“蛇油”几乎和偷牛一样危险。
《剑桥雅思真题8》Test B Section 2
Ask company employees questions prior to job interviews to gain as much insight as you can.
在面试前询问公司员工问题，以尽可能多地获得洞察力。
《剑桥雅思真题13》Test 2 Passage 2
Few chemicals have as positive a reputation as oxytoein.
很少有化学药品能像催产素那样有积极的名声。
(3)“not more...than...”表示“不比……更……”或“……和……一样”; “no more...than...”表示“与……一样不……”或“两者都不……”。
《剑桥雅思真题9》Test B Section 3
In terms of the physical strength involved, Rossy insists it is no more difficult than riding a motorbike.
就体力而言，罗西坚持认为骑摩托车并不会更难。
《剑桥雅思真题2》Test 1 Passage 2
This change is no more evident than in Western society to day.
这种变化并不比今天的西方社会更明显。
Lily is not more diligent than Susan.
莉莉不比苏珊勤奋多少。
2.不同等比较，表示人或事物的某一属性在比较之下程度不同。
(1)“not so/as...as”表示“不如，不及”。
《剑桥雅思真题7》Test 1 Passage 2
Fortunately—and unexpectedly—the demand for water is not rising as rapidly as some predicted.
幸运的是——出乎意料的是——对水的需求并没有像一些人预测的那样迅速增长。
《剑桥雅思真题8》Test B Section 3
This is not as difficult as it sounds.
这并不像听起来那么难。
《剑桥雅思真题10》Test B Writing Task 2
It is clear then that this situation is not as straightforward as it first appears.
很明显，这种情况并不像看上去那么简单。
《剑桥雅思真题13》Test 1 Passage 3
The advances are not as significant as the public believes them to be.
这些进步并不像公众所认为的那样重要。
(2)“more... than...”表示“比……多”, “less... than”表示“比……少”。
《剑桥雅思真题7》Test 4 Passage 3
Probably the most significant finding from research on noise is that its predictability is more important than how loud it is.
对噪音的研究可能最重要的发现是，噪音的可预测性比噪音的大小更重要。
《剑桥雅思真题8》Test 1 Passage 1
The calendars that were developed at the lower latitudes were influenced more by the lunar cycle than by the solar year.
在低纬度地区开发的历法受月球周期的影响大于太阳年。
《剑桥雅思真题10》Test 1 Passage 3
Research shows that peer power, used horizontally not vertically, is much more powerful than any boss's speech.
研究表明，水平而非垂直使用的同级权力比任何老板的讲话都要强大得多。
《剑桥雅思真题9》Test 3 Passage 1
Nevertheless, there is an alternative point of view that is concerned lesswith standards than with the facts of linguistic usage.
然而，还有一种不同的观点，与其说是关注标准，不如说是关注语言使用的事实。
《剑桥雅思真题4》Test 3 Passage 1
Many children may choose entrepreneurship because it allows them a degree of independence, is less exploitative than many forms of paid employment.
许多孩子可能会选择创业，因为创业让他们有一定程度的独立性，比许多形式的有偿就业更少受剥削。
