If more time given we can do it betterI ____(hear) him ___(sing) this song at that time.she ____(see)____(take)a walk by me yesterday.she ____(see)____(take)a walk by me this time yesterday.they ____(notice)____(hang) out two hours ago.I _____(often tell) ____(listen) to the teacher carefully in class.my mother often ———（make）me ——（do） 12 hours one day.帮一下忙I was hearinghim sing this song at that time.感觉这道题有歧义，就看你怎么理解at that time 了she was seen take a walk by me yesterday.she was seen taking a walk by me this time yesterday.这两道题我也觉得没什么意义，本来我上一道填的是taking，但为了和这道题的this time 所区分才选成take。语法上来讲都是没错的，重要的是你能理解see sb. do sth.和see sb. doing sth.的区别就行了they were noticed hanged out two hours ago.这里hang我理解成了吊死。I am often told to listening to the teacher carefully in class.my mother oftenmakes me do（do what？）12 hours one day.