帮我把这篇英语作文改成过去式,有不好的地方帮我修改一下
Lastweekend.Inthemorning,Igooutplaywithmygrandparents!Wecametothepark,wheretheairisgood,therearemanybeautifulflowersandtrees.Therearemanyelderlypeopleintheexercise,mygrandparentsaredoingtheexercise,thisisagoodplace.Intheafternoon,IwenttotheBoulderDam,Itookmanyphotos,Imetoneofmyclassmatesandhisparents,thisisahappySunday,Iamveryhappy.