Mary didin´t buy some books last year
did mary buy some books last year?
they didn´t go to cancun by plane
did they go to cancun by plane?
my parents didin´t work in a hospital many years ago
did my parents work in a hospital many years ago?
my son didin´t has two red cars
did my son has two red cars?
i didn´t make a chocolate cake
did i make a chocolate cake?
espero que esté bien y te sirva, sino entiendes algo dímelo, chao.