一般完成时用于描述过去发生的动作或状态对现在的影响，或者表示从过去某一时间开始一直延续到现在的动作或状态。以下是一些一般完成时的例句：

表示已完成的动作对现在的影响

I have studied English for 10 years.

They have been dating for 3 months.

I have finished my homework.

She has been to Paris twice.

表示一段时间内发生的动作

I have lived here since 1999.

She has lived here for ten years.

He has been to Japan three times.

表示刚刚完成的动作

I have just finished my homework.

She has just returned from the airport.

这些例句展示了一般完成时在表达不同时间范围内的动作或状态时的用法。希望这些例子能帮助你更好地理解一般完成时的用法。