输入GetKeyDown未触发

using System.Collections;
    using System.Collections.Generic;
    using System;
    using UnityEngine;

    public class Player : MonoBehaviour {

        public float moveSpeed;
        public float jumpHeight;

        // Use this for initialization
        void Start () {

        }

        // Update is called once per frame
        void Update () {

            Rigidbody2D playerBody = GetComponent<Rigidbody2D>();

            if (Input.GetKeyDown("space")){
                print("fired");
                //playerBody.velocity = new Vector2(playerBody.velocity.x, jumpHeight);
            }

            if (Input.GetKey(KeyCode.LeftArrow))
            {
                playerBody.velocity = new Vector2(-moveSpeed, playerBody.velocity.y);
            }

            if (Input.GetKey(KeyCode.RightArrow))
            {
                playerBody.velocity = new Vector2(moveSpeed, playerBody.velocity.y);
            }
        }
    }

我也试过了 Keycode.Space 而不是不起作用的“空间”

另外,出于某种原因,我不能移除或替换Unity3D标签,但它是用于二维Unity游戏。