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Which sentenceis most correct ;
1- I can not open the window as it has been screw shut
or
2- I can not open the window as it has been screwed shut
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Sentence 1 is not correct.

Sentence 2 is correct.
However, "can not" is usually written as one word:

- I cannot open the window as it has been screwed shut.
Comments  
I can not open the window as it has been screwed shut