take part in: meaning and explanation
To take part in something = to participate or be involved in something. e.g. I’m not very political now, but I took part in several big protests when I was younger.
Synonyms for take part in include: join in with something, participate in something, be involved in something.
Have a go at these micro-dictation exercises to hear this expression being used in context – how much can you understand?
About the sentence
…It had totally slipped my mind…
If something slipped your mind then you forgot it. This is a useful idiom to use when you’re apologising for something. e.g. I’m really sorry about not posting your letter – it slipped my mind.