Question：There have been criticisms of the product life cycle's usefulness as a forecasting tool. Identify the two reasons for this from the list below.
　　A. The product is affected by decisions made by the competitors.
　　B. The product is affected by internal decisions about the level of resources given to the product.
　　C. The product is affected by environmental issues outside the control of the company.
　　D. The product is affected by other products within the company's portfolio.
　　The correct answers are: The product is affected by environmental issues outside the control of the company; The product is affected by internal decisions about the level of resources given to the product
　　解析：The fortunes of a given product are affected by other products in the same company's portfolio, but these effects should be largely under the control of the company itself and thus may be taken into account during the forecasting process.
　　Decisions made by competitors would affect the product's position. This would have been included under the general heading of environmental issues.