1. I've changed my mind.
我改主意了。

2. I've had a change of heart.
我的想法变了。

3. I'll wait here. No, on second thoughts, I'll come with you.
我在这儿等吧。不，我还是跟你一起过去。

含蓄型：

1. Let me think about it again.
让我再想想吧。

2. We'll have to reconsider the whole thing .
我们不得不再重新考虑整件事。

装蒜型：

1. Did I really say that?
我那么说过吗？

2. Come to think of it, he did mention seeing you.
细想一下，他确实说过见过你。