فرق didn't و couldn't و wouldn't

didn't  مخفف کلمه ی did not  هستش که برای  زمان گذشته ی ساده استفاده میشه
I didn't go to school  -  من به مدرسه نرفتم
couldn't مخفف کلمه ی could not  هست که به گذشته ی فعل can  بر میگرده و یک فعل مدال(modal) هستش
 I couldn't go to school -  من نتوانستم به مدرسه بروم

wouldn't مخفف کلمه ی would not  هست که بهش گذشته در اینده هم گفته میشه و فعل مدال هستش  و استفاده های گسترده ای داره
i wouldn't go there - به انجا نمیروم