互补品
参考答案：是指两种商品中一种商品价格的上升会引起另一种商品消费量的减少，即两者是相互补充的关系。
Silk from China found its way to India, the Middle East and Rome, _______ spices and glass, which was not known to China.
A．in exchange for
B．in return
C．in change for
D．in need of
若作肺功能检查主要表现在
A．肺活量减少B．弥散功能降低C．残气量减少D．最大通气量增加E．第一秒钟用力呼气量减少
