Greg is designing a Scratch game in which the player moves a sprite by pressing the arrow keys. Greg writes the following scripts for the sprite:
Greg 正在设计一款 Scratch 游戏，玩家可以通过按方向键来移动精灵。Greg 为该精灵编写了以下脚本：

Chelsea suggests that Greg replace these scripts with the following:

Which of the following describe advantages of Chelsea’s suggestion over Greg’s original script?

I. If Greg wants to change the default speed the sprite moves at he only needs to edit one block rather than 4
II. It is easy for Greg to add functionality to the program to change the speed of the sprite based on the gameplay (e.g. slowing the sprite’s speed when injured)
III. It is clearer what the number used in the four movement scripts describes in the game.

Question

Greg is designing a Scratch game in which the player moves a sprite by pressing the arrow keys. Greg writes the following scripts for the sprite:
Greg 正在设计一款 Scratch 游戏，玩家可以通过按方向键来移动精灵。Greg 为该精灵编写了以下脚本：

Chelsea suggests that Greg replace these scripts with the following:

Which of the following describe advantages of Chelsea’s suggestion over Greg’s original script?

I. If Greg wants to change the default speed the sprite moves at he only needs to edit one block rather than 4
II. It is easy for Greg to add functionality to the program to change the speed of the sprite based on the gameplay (e.g. slowing the sprite’s speed when injured)
III. It is clearer what the number used in the four movement scripts describes in the game.

BlackTom AI · Accepted Answer

Question restatement: Describe advantages of Chelsea’s suggestion over Greg’s original Scratch scripts for moving a sprite with arrow keys, given the options I, II, and III.

Option I: If Greg wants to change the default speed the sprite moves at he only needs to edit one block rather than 4
- This is true because Chelsea’s approach typically introduces a single speed variable that multiple movement directions reference. When speed is centralized, adjusting it requires changing only one value, not four separate move steps in different scripts. It reduces duplication and makes global speed changes straightforward, which aligns with good programming practice of reducing repeated code.

Option II: It is easy for Greg to add functionality to the program to change the speed of the sprite based on the gameplay (e.g. slowing the sprite’s speed when injured)
- This follows from the same centralized speed design. If speed is stored in a single variable, gameplay-triggered changes (like a speed boost, slow-down, or a debuff) can be implemented by modifying that variable (or applying a multiplier) rather than altering multiple independent movement blocks. This enhances extensibility and maintainability, making it easier to respond to game-state changes.

Option III: It is clearer what the number used in the four movement scripts describes in the game
- When movement is driven by a single speed variable rather than hard-coded values in each movement block, the meaning of the numeric value becomes explicit. The number represents the current speed of the sprite, not just an arbitrary constant in four separate scripts. This improves readability and reduces confusion about what the numbers control in each movement block.

Overall reasoning across options: Each point highlights a facet of why centralizing speed control using a single variable (as in Chelsea’s suggestion) benefits code quality. Option I emphasizes easier global speed changes. Option II focuses on extensibility and responsive gameplay adjustments. Option III stresses improved clarity and readability of what the numeric values signify. None of the statements relies on a misunderstanding of how speed is applied; rather, they collectively describe how a single speed parameter simplifies modification, enhances adaptability to gameplay events, and clarifies the code’s intent. The ideas are complementary rather than mutually exclusive, and together they capture the practical advantages of Chelsea’s restructuring over the original separate-move scripts.

(72ab92) AP CS Principles (72ab92) AP 计算机科学原理 1.9 Additional Practice 1.9 附加练习

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