A scratch application consists of just one sprite, which is the crab sprite shown belowWhen the space key is pressed, the crab begins to change depending on the position of the mouse pointer.When the mouse pointer is positioned to the left of the crab, the crab rotates in an anti-clockwise direction with its claws closed. Once the crab faces left, it stops rotating and its claws become bigger and open.When the mouse pointer is positioned to the right of the crab, the crab rotates in a clockwise direction with its claws closed. Once the crab faces right, it stops rotating and its claws become bigger and open. Watch the short video to see how the program is meant to behave. https://lms.monashcollege.edu.au/pluginfile.php/4632927/question/questiontext/5694120/17/56959379/qu3.mp4 Video Player is loading.Play VideoPlayMuteCurrent Time 0:00/Duration 0:45Loaded: 100.00%0:00Stream Type LIVESeek to live, currently behind liveLIVERemaining Time -0:45 1xPlayback Rate2x 1.75x 1.5x 1.25x 1x, selected 0.75x 0.5x ChaptersChapters Descriptionsdescriptions off, selected Captionscaptions settings, opens captions settings dialog captions off, selected Audio TrackPicture-in-PictureFullscreenThis is a modal window.Beginning of dialog window. Escape will cancel and close the window.TextColor[select: White, Black, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Opaque, Semi-Transparent]BackgroundColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Opaque, Semi-Transparent, Transparent]WindowColor[select: Black, White, Red, Green, Blue, Yellow, Magenta, Cyan]Transparency[select: Transparent, Semi-Transparent, Opaque]Font Size[select: 50%, 75%, 100%, 125%, 150%, 175%, 200%, 300%, 400%]Text Edge Style[select: None, Raised, Depressed, Uniform, Dropshadow]Font Family[select: Proportional Sans-Serif, Monospace Sans-Serif, Proportional Serif, Monospace Serif, Casual, Script, Small Caps]Reset restore all settings to the default valuesDoneClose Modal DialogEnd of dialog window. The code shown below is the code for the crab sprite. It is incomplete. Complete the code for the crab sprite to produce the desired effect. 1. 2. 3. 4.

Question

BlackTom AI · Accepted Answer

The task describes completing a Scratch script for a crab sprite so that when the space key is pressed, the crab rotates toward the mouse and changes its claws from closed to open once it faces left or right. The logic must cover both possible mouse positions (left of the crab and right of the crab) and must implement two distinct states for the claws (closed, then open) along with the rotation behavior.

Option a (3): This would imply there are only three blocks to implement the entire left and right rotation and claw-opening behavior. However, you need separate logic paths for both directions, plus a condition to switch costumes, plus a control to rotate until the crab is facing the target direction, and finally a state to wait for the rotation to complete before switching the claws to open. Three blocks are almost certainly insufficient to represent all these steps in a clear, reliable way.

Option b (1): A single-block solution cannot encode any conditional behavior or sequencing. With only one block, the crab would not be able to determine if the mouse is to the left or right, would not rotate toward the correct direction, and would not switch between claw states. This is clearly inadequate for the described multi-step interaction.

Option d (2): Two blocks still cannot capture the necessary branching (left vs right), the rotation toward the mouse, and the subsequent costume change to open claws. At minimum, you need a conditional structure to check the mouse position relative to the crab, a rotation operation that runs until facing the chosen direction, and a costume change tied to the facing direction. Two blocks do not provide enough granularity to implement all these steps reliably.

Option c (4): Four blocks give enough room to implement the essential steps in sequence and with branching. You can imagine a structure like: when space pressed, if mouse is left of crab then rotate toward left (until facing 180) and switch to claw-closed costume, then (optionally) wait until facing left and switch to claw-open costume; else if mouse is right of crab then rotate toward right (until facing 0) and switch to claw-closed costume, then wait until facing right and switch to claw-open costume. This arrangement supports both directions, ensures the crab rotates toward the correct target, and coordinates the claw state changes.

In summary, options a, b, and d each fail to provide enough blocks to represent the necessary branching, rotation control, and costume changes. Option c is the only choice that plausibly provides a complete structure to achieve the described behavior with the four essential elements: directional check, rotation toward the target, initial claw state, and subsequent claw-opening state.

类似问题

Which of the following trees corresponds to a potential parse of the ambiguous sentence below, with correct syntactic categories? Some diagnostics are provided.

Which of the following sentences contain two non-finite verbs? Select all that apply.

Analyze the following sentence: The sentence contains [ Select ] 8 6 5 7 3 4 functional words, [ Select ] 2 3 1 4 5 count nouns, [ Select ] 4 5 2 1 3 mass nouns, and [ Select ] 1 5 2 3 4 adjectives.

You own a bond that pays $64 in interest annually. The face value is $1,000 and the current market price is $1,021.61. The bond matures in 11 years. What is the yield to maturity?

Which of the following statements is CORRECT?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单