Simone
今天课上刚讲的：
Quantity demanded : A movement along a demand curve(需求曲线）is a result of a price change alone . This is know as a change in the quantity demanded .
Demand : A shift（位移） in the entire curve occurs when something other than the price changes. This is a change in demand . （如下图所示）
By Dirk Mateer
结合这幅图表我们可以看出，quantity demanded是会根据单独的价格变化而变化，demand是会根据价格以外的因素而变化。
希望能帮到你。
demand 需求
每段时间内愿意购买的货物的数量
quantity demanded 需求量
某特定价格下消费者愿意购买的总数量
需求的变动是由于价格以外的因素所引起的变动 需求量的变动是因为单独的价格变化所引起的 需求量增加或减少。在图像上反映为需求量沿着曲线增加或减少，
需求减少或增加，是整条曲线的左右平移
如果一个商品的自身价格（因为自身价格是需求量的主要影响因素）降低，它的需求曲线不会左右移动。但是在曲线上的点会下移，称为an increase in the quantity demanded。但如果是其他因素，比如消费者的收入，品味，同类物，互补物和未来预期产生变化，需求曲线就会左右移动。称为an increase/decrease in demand.经济学家就是用“quantity"的有无来区分这两种变化。
⬆️以上内容是我学AP里看到的，希望多少有帮助到你～
“Remember a change in the price of the item of interest is a change in quantity demanded and is graphed by a movement along the curve. This is compared to a change in demand which is caused by a change in one of the non-price determinants of demand and graphed by shifting the curve.”
补充一些影响的因素
Important demand shift factors includes: 1.society’s income 2.the price of other goods( substitute & complement goods) 3.tastes 4.expectations 5.taxes and subsidies to consumers
Demand means the whole market, which is the quality of a products that consumers are willing and able to buy at different prices.
Effective Demand is the demand that could be bought given the buyers are willing and able.
【不知道自己在讲什么，随便看看吧
