{
"items" : {
"Chemistry" : {
"-KiUOPW8TR_QcEeDbrAy" : {
"answer" : "ssssss",
"id" : "1",
"question" : "sss"
}
},
"Countries" : {
"-KiUR2ilBYN5LJU6uOCf" : {
"answer" : "ffffff",
"id" : "1",
"question" : "fffff"
}
},
"Film" : {
"-KiUOr7GbPhV_perbHt4" : {
"answer" : "dddd",
"id" : "1",
"question" : "dd"
}
}
}
根据上述数据,我只想获取项目的子名称。
例如,我想获取这些名称
Chemistry
Countries
Film
我该怎么做?