investment既可以用作可数名词，也可以用作不可数名词。用作可数名词时，有复数形式。
1. 不可数名词 N-UNCOUNT 投资（这种行为）Investment is the activity of investing money.
He said the government must introduce tax incentives to encourage investment... 他说***必须推出税收激励政策来鼓励投资。
One of the most important changes concerns the investment of pension ontributions.
最重要的一个变化涉及养老保险基金的投资。
2 既可以用作可数名词，也可以用作不可数名词 N-VAR 投资金额;投资物An investment is an amount of money that you invest, or the thing that you invest it in.
