That's an interesting question. I'm assuming you have internet considering you are a member on Scratch. Are you just asking for curiosity? Unfortunatley, I don't know the answer.
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Sure, you can put Scratch on another computer without using the internet. Just download the install program (using a computer that does have internet) and save it to a flash drive or a CD. Then, take the install program to the computer that doesn't have internet and run the install program from the flash drive or CD.
The off-line computer will then have Scratch, however it will not be able to share projects on the web site since you need an internet connection for that part to work.
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