Using The Present Perfect ('Have Done')

source: Oxford Online English        2014年1月3日
The full lesson (with text and exercises):
Look at these sentences:
- I've been to Italy
- He's eaten four pieces of cake already this morning
- They haven't arrived yet
These sentences all use the present perfect tense. But, what is the present perfect, what does it mean, and how should you use it? How is it different from the past simple? This lesson will introduce this topic and answer these questions.

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