[{key:1,students_replies:[{Date:20210101,replies:[{name:"jack",reply:"I do not like this idea"},{name:"jason",reply:"I would rather stay at home"},{name:"charles",reply:"I have an plan to improve"},]},{Date:20210401,replies:[{name:"lucy",reply:"can not agree"},{name:"tason",reply:"do not care"},{name:"charles",reply:"whatever"},]},{Date:20210801,replies:[{name:"william",reply:"can not agree"},{name:"from_jason",reply:"do not care"},{name:"charles",reply:"whatever"},]}]},{key:2,students_replies:[{Date:20210201,replies:[{name:"jack",reply:"I do not like this idea"},{name:"jason",reply:"I would rather stay at home"},{name:"charles",reply:"I have an plan to improve"},]},{Date:20210501,replies:[{name:"lucy",reply:"can not agree"},{name:"tason",reply:"do not care"},{name:"charles",reply:"whatever"},]},{Date:20210701,replies:[{name:"william",reply:"can not agree"},{name:"lily",reply:"do not care"},{name:"charles",reply:"whatever"},]}]},{key:3,students_replies:[{Date:20210301,replies:[{name:"jack",reply:"I do not like this idea"},{name:"jason",reply:"I would rather stay at home"},{name:"charles",reply:"I have an plan to improve"},]},{Date:20210601,replies:[{name:"lucy",reply:"can not agree"},{name:"tason",reply:"do not care"},{name:"charles",reply:"whatever"},]},{Date:20210901,replies:[{name:"william",reply:"can not agree"},{name:"jason jordan",reply:"do not care"},{name:"charles",reply:"whatever"},]}]}]

db.collection.find()