第21步：现在这些障碍物正从控制台中间开始移动。让他们从控制台的右边开始！
- 在你的代码中找到两个小行星。记住，这些是位于代码行 Sprite at Position 。
- 将两个石块图像标签之后的第二个参数d都更改为 300。
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stage.set_background("space")
sprite = codesters.Sprite("spaceship")
sprite.set_size(0.5)
sprite.go_to(-200, 0)
stage.set_gravity(10)
stage.disable_all_walls()
def space_bar():
sprite.jump(5)
# add other actions...
stage.event_key("space", space_bar)
def interval():
top_height = random.randint(50, 300)
# sprite = codesters.Sprite("image", x, y)
top_rock = codesters.Sprite("asteroid", 0, 0)
top_rock.set_height(top_height)
top_rock.set_gravity_off()
top_rock.set_y_speed(0)
top_rock.set_top(250)
bot_height = 350 - top_height
bot_rock = codesters.Sprite("asteroid", 0, 0)
bot_rock.set_height(bot_height)
bot_rock.set_gravity_off()
bot_rock.set_y_speed(0)
bot_rock.set_bottom(-250)
top_rock.set_x_speed(-2)
bot_rock.set_x_speed(-2)
# add any other actions...
stage.event_interval(interval, 2)
