Questions & Answers about Datamaskinen er i bruk nå, så jeg kan ikke slå den av.
Datamaskinen is the definite form (the computer), made by adding -en to the noun (datamaskin + -en).
You’d use en datamaskin if you mean a computer (not a specific one). In this sentence, it’s clearly a specific computer we already know about.
er i bruk is an idiomatic phrase meaning is in use / is being used.
bruker would mean uses (active: the computer uses…), which doesn’t fit here.
If you want a single-verb alternative, you could say Datamaskinen brukes nå (The computer is being used now), but er i bruk is very common and natural.
Because så here introduces a new main clause meaning so/therefore. In Norwegian, it’s standard to separate two main clauses with a comma when they’re linked this way:
- Datamaskinen er i bruk nå, så jeg kan ikke slå den av.
You can also split it into two sentences: - Datamaskinen er i bruk nå. Så jeg kan ikke slå den av. (less common as a standalone Så-sentence, but possible in informal style)