How to unblock a school computer

You turn your computer on and the computer will not boot up where is something you should do to diagnose the problem?

How do you take a green screen out of the video while editing?

Consider the usual algorithm to convert an infix expression to a postfix expression. suppose that you have read 10 input characters during a conversion and that the stack now contains these symbols: (5 points) | | | + | | ( | bottom |_*_| now, suppose that you read and process the 11th symbol of the input. draw the stack for the case where the 11th symbol is