cost的过去式怎么写

例句：

And again, we must think of the cost.

再说，我们必须考虑成本。

Just out of interest, how much did it cost?

我只是好奇问问，这个花了你多少钱？

How much will it cost, more or less?

这个大概得花多少钱？

The total cost to you is  3 000.

你总共要支付3000英镑。

How much does it cost to become a member?

要成为会员得花多少钱？