A recent article suggests that the introduction of the new iPhone 5 increased the demand for iPhone protective cases. The article suggests that these two goods are (最近的一篇文章表明,推出新的iPhone 5增加了对iPhone保护壳的需求。文中提到这两种商品是——中文由在线翻译而来,仅供参考)
A.
substitutes and their indifference curves are close to being straight lines.替代品及其无差异曲线接近于直线。
B.
complements and their indifference curves are close to being straight lines.补充和他们的无差异曲线接近直线。
C.
substitutes and their indifference curves are close to being L shaped.替代品和他们的无差异曲线接近于L形。
D.
complements and their indifference curves are close to being L shaped.补充和他们的无差异曲线接近L形。