Sometimes, by buying something cheap now, you will be costing yourself more in the long run.
有时候你花了很少钱买了便宜货,但它日后可能要花掉更多的钱。
I know. Save your breath!
早就知道了,还用你说!
and near its lower reaches there is a long tailing-off which is almost certainly the result of material transported out to deep water after being eroded from the continental masses.