fill in:can/can`t or could/couldn`t
When i was younger,i didn`t know the first think about computers.I 1).......... even turn it on! One day, i saw an ad about free computer courses at the community centre.In no time,i 2)........... use a computer like an expert.Today, i`m a computer programmer and i 3)........... not only use it , but i actually make new programmes for it.I love computers and i 4)........... imagine my life without them.