lower 是个形容词或者动词，did是个动词需要副词less修饰

lower只能做形容词,不能修饰动词rose;
high/low 不能修饰动作，只能修饰名词。more/less才可以修饰动作，也可以修饰名词。

D low不能修饰动词，只能修饰名词。如果D要正确，需要是 lower than the percentage (they did)

5个选项都没有percentage/that去指代2.8%，所以可以判断是动作比较。high/low 不能修饰动作，只能修饰名词。more/less才可以修饰动作，也可以修饰名词。

错选了D. "lower"不可用于可数名词。

if choice D said 'less' it would be fine. the only problem with that choice is that 'lower' cannot modify actions.

"Lower" and "greater" can't be used to compare actions.

The meaning should be clear: The costs rose by 2.8% this past year; in the previous year, they rose by more than 2.8%. So, this year, they rose less than they did last year.

曼哈顿185页

比较结构中是主语+不及物动词，后面可以省略主谓没有歧义

lower low 都是副词
F. less than 错 比较的是employment costs还是2.8%？

请问这里为什么是less而不是fewer？costs作为复数名词，less不是只能修饰不可数吗？

这里说的是costs，需要用less 和more 来形容。costs 是复数。总上两点，在AC中选择。
Rose是动词，因此是A

less表示smaller in size, amount, degree....
lower是higher的对立面

costs rose 2.8 percent in X, less than costs rose in Y.

这里后面的costs rose和前面完全一致，所以可以改写成

costs rose 2.8 percent in X, less than they did in Y.

than大平行，costs复数对应they，rose对应did，排除bcde，还有题是did** sth adjer than ** were，不过那个是把名词进行的比较才用were

DE:Idiomatic usage. In the phrase 'little of X', the X has to be a singular quantity. If it's plural (like 'differences'), then you have to use few.
There was very little food left over at the end of the party.
There were very few crab cakes left over at the end of the party

1) the number is lower than the other number
2) the task has a priority lower than that task
3) the ceiling in my new house is lower than that in my old house.

为什么后面: slightly.....不能理解为是2.8percent的修饰啊
不理解为什么D错，求解救。。

less不是用于不可数吗 这里costs可数啊

讲到钱啊 什么的不都是单数的概念吗，为什么employment costs是复数呢，不应该是一笔的概念吗。

你把句子内容都补齐，than前后应该完全平行，这个句子应该是：

costs rose 2.8 percent in X, less than costs rose in Y.

这里后面的costs rose和前面完全一致，所以可以改写成

costs rose 2.8 percent in X, less than they did in Y.