Here are the correct answers for the sentences you provided:

**16. Read the sentences and underline the correct answer:**
1. My brother **streams** his files on his computer but doesn't back them up.
2. You can connect a series of computers together on a **network**.
3. I prefer to use a **laptop** as I can work from anywhere.
4. Stop playing games! **Shut down** your computer right now!
5. I don't like paying a lot of money for **apps**, but it can cause problems if you only **download** them for free.

**18. Complete the sentences using the words in the box:**
1. A set of pages of information on the internet about a particular subject. **website**
2. A copy of the files from your computer that you keep in a different place. **backup**
3. A machine, like a smartphone, that can connect to the internet. **device**
4. A file, like an essay, that you add to an email before sending it. **attachment**
5. This happens when your computer suddenly stops working. **crash**
6. Music or video that you watch on the internet without downloading it first. **stream**