Read the sentences and decide which one of the given words fits each gap in the expressions:
1. There was a fire and they had to shut ______ the main computer.
2. It takes ages for my computer to boot ______ in the morning. I turn it on and go off for a coffee.
3. Remember to switch this ______ when you are not using it to save power.
4. We cannot access the file. The computer has gone ______ .