1.hear和see是感官动词,意思分别是“听起来”和“看起来”,它们后面可以接动词原形或者是动词ing的形式.
hear/see sb do sth看见或听见某人做某事的全过程.例如:I hear/see him sing in the classroom.我听见/看见他在教室里唱歌(全过程)
hear/see sb doing sth看见或听见某人正在做某事.I hear/see him singing in the classroom.
我听见/看见他正在教室里唱歌.
2.forget to do sth 意思是:忘记要做某事
forget doing sth 意思是:忘记做过某事
remember to do sth 意思是:记得要做某事(别忘记做某事)
remember doing sth 意思是:记得做过某事