Question: Which sentence is an example of a common error in passive voice?

Options:

1. The homework was completed by the students.
2. The students completed the homework.
3. The homework completed by the students.
4. The homework is being completed by the students.

Correct Answer: The homework completed by the students.

Solution:

The sentence \'The homework completed by the students.\' is incorrect because it lacks a form of \'to be\' to indicate passive voice.