Study the rule and type because or because of to complete the sentences
The Rule
We use "because" with the clause.

Example: We are happy because our baby was born.

We use "because of" before the noun.

Example: Our flight was cancelled because of the fog.

1. All of my colleagues were tired
   [ ]
   they had been working all day.
2. I was late
   [ ]
   the accident that I had seen.
3. We didn't watch the whole film
   [ ]
   it was so boring.
4. I couldn't join my classmates on a school trip
   [ ]
   my broken arm.
5. The teacher can't hear anything
   [ ]
   the noise.
6. I didn't do my homework
   [ ]
   I couldn't find my school bag.