i had a bad headache yesterday,soi didn 't go to school > if i i can't look up the new words because i don't have a ditionary > if i

I had a severe headache, considering I did not go to school
> if I have no headache then I can go to school
I can't look up new words because I don't have an option
> if I can look it up I have the option

Chúc bn học tốt!!

I had a bad headache yesterday, so I didn't go to school ( câu đk loại 3)

-> If I hadn't had a bad headache yesterday, I wouldn't have gone to school.

I can't look up the new words because I don't have a dictionary. ( câu đk loại 2)

-> If I had a dictionary, I would look up the new words.

Chúc bạn học tốt

Xin hay nhất, tks!!