health
to keep in good health 选名词,固定搭配
保持身体健康
eg：How can you keep in good health?
你怎么可能保持健康呢?Can you tell me the ()[是填differences 还是 difference] in price between this hat and that hat请说明原因 为什么选differences difference是可数名词，这里要用复数，因为不同不止一个可能许多