Translation:That worker wears black pants.
"The worker wears black pants" should be acceptable too, I think.
...and so should “the worker wears a pair of black pants.”
Then report it. That's the only way they can improve the course.
The problem is that the option to report an incorrect English sentence is not always given.
I think 'trousers' should also be an acceptable translation of 'celana'?
"The worker wears a pair of black pants", actually agree with all the preceding comments.