At __________________ should exist correct mains voltage. A: the transformer B: connecting transformer C: disconnecting transformer D: pre-disconnecting transformer

At __________________ should exist correct mains voltage. A: the transforme B: connecting transforme C: disconnecting transforme D: pre-disconnecting transforme

5. Which of the following is not a way to avoid viruses? A: Use a firewall. B: Be careful about unknown messages C: Do not surf. D: Disconnecting from the Internet.