The present perfect tense is formed with 'have/has' + past participle.

What is the main difference between 'I lost my key' and 'I have lost my key'?

• The first sentence means the key is still lost, the second means it's found.
• The first sentence describes a past event, the second emphasizes the current result.
• There is no difference in meaning.
• The first sentence is a question, the second is a statement.

The sentence 'Somebody has taken my umbrella' implies that the umbrella is still missing now.

Which sentence uses the present perfect tense correctly to describe an experience?

• I have visited Paris last week.
• I visited Paris last week.
• I have visited Paris before.
• I visited Paris yesterday.