As Brian said, "taken" and "given" are verbs in *perfect tense*. In English, you have different ways to talk about the past.
For example:
Past indicates that something happened in the past:
I took the bus to school. (Then I sat down in the classroom and talked to my friend...)
I ate a cake made of onions. (Because I had one in the fridge.)
Perfect tense is used to stress that something has *already* happened.
I have taken the bus to school. (But I didn't like it, going by bike is much more fun!)
I have eaten a cake made of onions. (On a holiday in France.)
I hope this helps.
