rise or fall in price的意思|示意

Speculators, by contrast, buy and sell securities based on whether they believe those securities will next rise or fall in price.

投机者，相比之下，购买和出售证券取决于他们是否认为这些证券的价格将上升或下降。

Such systems are sometimes used to set motorway tolls (which rise and fall with demand in an effort to keep traffic flowing), or to adjust the price of energy in electricity markets.

这一机制有时会被用于设置高速公路通行费(为保证交通顺畅，通行费因需求而上涨、下调)，或者用于调整电力市场上能源价格。