忘记的英文单词是forget。
forget的用法是：
1. forget to do表示忘记还没做的事情，例如I am sorry I forgot to return the library book，意思是对不起，我忘记归还图书馆的书了。
2. forget doing表示忘记已经做过的事情，例如He forgot going to Shanghai with his parents when he was five years old，意思是他忘记了五岁时曾跟父母去过上海。
3. forget that表示从句，例如Never forget that you are loved，意思是永远不要忘记你所爱的人。