中4econ需求問題

直接的原因是：『香港有更多學校實施閱讀計畫以培養學生的閱讀習慣…』是會增加需求但不會影響需求量因為書本的價格沒有變動，而書本的供應量會因學生對書本的需求增加而增加。

wilson625_hk的答案更易明可取：
以上例即需求曲線向右移(需求增加)，供應曲線不變；但供應量因需求曲線向右移而增加[按：需求量也當然增加的(理論上：需求量=供應量)，不過不在選擇中了]。

You should make a clear concept between "Demand 需求 and Quantity demanded需求量" and "Supply 供應and Quantity supplied供應量".

The increase in demand (shift the demand curve to right side) is due to the outside reason. Eg. 更多學校實施閱讀計畫以培養學生的閱讀習慣, the demand for books will increase and so the demand curve will shift to right.
It is not shift along the original supply curve.

Similarly, the supply of book has no change because there is no any effect on supply curve, therefore the supply curve will remain unchange. However, the shift of demand curve will cross the original supply curve and make a new equilibrium price and a new equilibrium quantity. You should know that the new equilibrium quantity is greater than the original equilibrium quantity. Therefore, 供應量will increase.

Hope you can learn what I mean.

由於學校實施閱讀計畫以培養學生的閱讀習慣,令學生對書本ge需求上,但係供應曲線無移動,而供應量則上升。

2006-12-12 21:38:36 補充：
令學生對書本ge需求上升