Present perfect or past simple?

I ____________ before

• 've never driven

• didn't drive

I ____________ school when I was 16

• 've left

• left

I ____________ a foreign country.

• 've already visited

• already visited

I ____________ my university studies yet.

• haven't finished

• finished

I ____________ my best friend for the last ten years.

• 've known

• knew

I ____________ on a plane.

• 've never been

• never went