问-如何连接4个表？

EN

class Membership < ApplicationRecord
  belongs_to :user
  belongs_to :group
end

class User < ApplicationRecord
  has_one :user_score
  has_many :memberships
  has_and_belongs_to_many :groups, through: :memberships # an user can be owner or member of a group
end

class Group < ApplicationRecord
  has_many :memberships
  has_many :members, through: :memberships, source: :user
end

class UserScore < ApplicationRecord
  belongs_to :user
end