Nie rozumiem 'd

to skrócona forma od "he had"
czasownik be do have i jeszcze parę mają skrócone formy

I am I'm I have I've I had I'd
he is he's he has he's he had he'd
she is she's she has she's she had she'd
we are we're we have we've
you are you're
they are they're
to sa niektóre,ale w każdej książce od gramatyki coś na ten temat znajdziesz