ImageCollection（错误）DateRange：错误的日期/时间“2020-12-21”、“2021-03-21”

Question

/*
//season dates
var spring = image.filterDate('2020-03-20', '2020-06-20')
var summer = image.filterDate('2020-06-20', '2020-09-20')
var autumn = image.filterDate('2020-09-20', '2020-12-21')
var winter = image.filterDate('2020-12-21', '2021-03-21')
*/

var season_dates = [
("2020-03-20'" + ' , ' + "'2020-06-20"),
("2020-06-20'" + ' , ' + "'2020-09-20"),
("2020-09-20'" + ' , ' + "'2020-12-21"),
("2020-12-21'" + ' , ' + "' 2021-03-21")
  ];

console.log(season_dates);


for (var i = 0; i < season_dates.length; i++) {
    var SEASONS = 
    (
      image.filterDate(season_dates[i])
     );
}
console.log(SEASONS)

我试图让 for 循环代表各个季节日期变量。错误中的输出包含一个相同的字符串。我错过了什么？