The present perfect is a grammatical combination of the present tense and perfect aspect that is used to express a past event that has present consequences.

We often use the present perfect to say what we've done in an unfinished time period, such as today, this week, this year, etc., and with expressions such as so far, until now, before, etc.

Some examples:

They've been on holiday twice this year.
I'm sure I've seen that film before.

You can check your knowledge about the topic by taking a short lesson or if you want to do it from scratch, I also offer longer class options.

现在完成时是现在时和完成体的语法组合，用于表达对现在产生影响的过去事件。

我们经常用现在完成时来表达在未完成的时间段内所做的事情，比如今天、本周、今年等，以及诸如到目前为止、直到现在、之前等表达方式。

一些例子：

他们今年已经度假两次了。
我肯定我以前看过那部电影。

您可以通过参加简短的课程来检查您对该主题的了解，或者如果您想从头开始学习，我还提供更长的课程选项。