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... 他说政府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.

...an investment of twenty-eight million pounds... 2,800万英镑的投资金额

You'll be able to earn an average rate of return of 8% on your investments. 你将能获得 8% 的平均投资收益率。

3 可数名词 N-COUNT 有用的投资物;值得买的东西If you describe something you buy as an investment, you mean that it will be useful, especially because it will help you to do a task more cheaply or efficiently.

When selecting boots, fine, quality leather will be a wise investment... 在挑选长筒靴的时候,购买上等的好皮靴将是明智的选择。

A small-screen portable TV can be a good investment. 小屏幕的便携式电视机很值得买。

4 不可数名词 N-UNCOUNT (时间、精力的)投入Investment of time or effort is the spending of time or effort on something in order to make it a success.

I worry about this big investment of time and effort. 我担心投入这么多时间与精力却不起作用。