MongoDB选择_id数组的位置？

{
  "_id": 1,
  "name": "Alice",
  "scores": [80, 90, 95]
}

db.students.find({}, {"scores.0": 1})

{
  "_id": 1,
  "scores": [80]
}

db.students.find({}, {"scores.1": 1})

{
  "_id": 1,
  "scores": [90]
}

db.students.find({}, {"scores": 1})

{
  "_id": 1,
  "name": "Alice",
  "scores": [80, 90, 95]
}