需求量变化的英文：
change in quantity demanded

change是什么意思：
n. 变化；交换，交替；零钱
v. 改变；交换，替换；兑换；更换

change a bed;change the baby.
换床单；给婴儿换尿布

We propose 'a change [making a change / to make a change / that a change should be made].
我们建议应做一点改变。

The change of quantity can causes the change of quality.
量变可以引发质变。

quantity是什么意思：
n. 量，数量，许多，大量

dimensionless quantity
无因次值|无量纲的量

Bill of quantities: The specification of the quantity of materials to be used.
工程量清单;建筑工程清单;数量清单:指项目所用材料的数量及其规格的清单。见priced bill of guantities

Quality is better than quantity
不求其多,但求其精

demanded是什么意思：
n. 要求，所需之物；需求，需要
v. 要求；询问，质问；命令；需要

It is the demand, stupid.
傻瓜，答案是需求。

Demand exceeds supply. The supply is not adequate to the demand．
供不应求

I demand a recount.
我要求重算。