orget to do sth 忘记要去做某事 forget doing sth 忘记以前曾经做过某事 例如 Sorry,I forgot to bring the book.(对不起，我忘了带书了。) I forgot borrowing a book from you.（我忘记曾经向你借过书这件事）
forget to do sth忘记去做某事，指还没做的事如 Don't forget to post a letter for me .别忘了帮我邮信 forget doing sth 忘记做过某事这事已经做了如 I forget seeing you somewhere.我忘记了在什么地方见过你。
