1)构成比较额连词搭配错误或者不完整 as..as… more..than..
通常出现的错误形式有as…than… more…as; More rather than
不完整的情况有as many后面缺少as/more 后面缺少than
2)构成比较的形容词/副词和修饰对象的搭配错误
例句：A study commissioned by the Department of Agriculture showed that if calves exercise and associated with other calves, they will require less medication and gain weight quicker than do those raised in confinement. (A) associated with other calves, they will require less medication and gain weight quicker than do (E) associate with other calves, they require less medication and gain weight more quickly than
Quicker than和 more quickly than 选后者 E
3)比较结构的冗余：as many as, more than同时出现的结构
In a recent poll, 86 percent of the public favored a Clean Air Act as strong or stronger than the present act.
(A) a Clean Air Act as strong or stronger than
(B) a Clean Air Act that is stronger, or at least so strong as,
(E) a Clean Air Act at least as strong as
答案是E A as strong or stronger than同时出现 直接as strong as
B 多加了一个插入语 at least so strong as
E 正确简洁
4)几组形容词的比较级区别
① Less 指的是数字和量小，通常是不可数
There is less water in the bucket than in the pool.
I have been trying to cut back, so now I drink less coffee.
② Fewer指的数量小，通常是修饰可数名词
Express checkout: 10 items or fewer.
Gene has read only a few books on the assigned reading list.
③ lower 修饰程度
The average temperature is lower in the winter than in the summer.
Lower the water level in the pool by pulling the drain plug.
④ Amount: quantity
Degree: level or amount.
Larger/smaller ?size, amount, or number
Greater ?degree = greater level or amount
Higher/lower ?number + amount
size并不是一个测度，而是how big or small something is，一个程度
形容amount和number的时候三者都可以用higher, larger, greater。
形容size的时候可以用只larger。
形容level(程度)的时候只可以用greater。