1. value和worth指某物的实际价值，属永久的和不变的东西。
2. cost指某一工作、商品所需花费的成本或代价。
3. price指某商品出售的价格。
   What's the price of rice?大米的价钱是多少?
   The cost of living is much higher now than it was.现在的生活费用比以前高多了。
   How much is it worth?=(What is it worth?)这值多少钱?