The present perfect simple tense can be used to show something that started in the past and has not yet finished. It’s formed by the verb to have and the past participle. What’s a past participle, you say? For regular verbs, it’s the same as the past simple: just add –ed. For the irregular verbs, you just have to memorize the form.

Take a look at these examples with the regular verb to work:
- I have (I’ve) worked here for two years now.
- He has (he’s) worked here for two years.
- They started working here in the past, and they are still working here now.

Take a look at this example from the dialogue using the irregular verb to have:
I’ve had a crush on her for ages.
I had a crush on her in the past, and I still have a crush on her now.

Note: In spoken English, we usually use the contractions I’ve worked, he’s worked, and so on.