Read the sentences and decide which one of the given words fits each gap in the expressions:
1. You need to log ______ before you can start using it.
2. It takes ages for my computer to boot ______ in the morning. I turn it on and go off for a coffee.
3. You need to switch it ______ using this button before you can use it.
4. They were able to hack ______ Microsoft's system and steal the passwords.