以下是我的routes.rb文件：

Rails.application.routes.draw do
  #Routes
  get 'users/s/:username', to: "users#search"
  resources :users, only: [:index, :show, :create, :update, :destroy]
  resources :forum_threads, only: [:index, :show, :create, :update, :destroy] do
    resources :comments, only: [:index, :show, :create, :update, :destroy]
  end
end

这是我的控制器中与注解相关的部分：

class CommentsController < ApplicationController
    #GET /Comments [Get all comments for a specific thread]
    def index
        @Comments = Comment.where("ForumThread_id = ?", params[:forum_thread_id])
        render json: @Comments
    end

    #GET /Comments/:id [Get a specific comment by its ID]
    def show
        @Comment = Comment.find(params[:id])
        render json: @comment
    end

我尝试通过Postman发送请求。index方法似乎可以用于注解（as seen here），但show方法似乎不起作用（like here）。为什么show方法不起作用？