Don't forget __ __ __ __ the teacher怎么填急用

Don't forget __ __ __ __ the teacher怎么填
急用

don't forget to do sth 表示不要忘记去做sth ,表示这件事情还没有做
don't forget to doing sth 表示不要忘记做过sth 这件事情已经做过了