What will be the passive of this questions?
They are sending Mr. Smith abroad for business?
They are examining the student now?
1) Mr. Smith is being sent abroad for business?
Notice, here "by them" has been omitted because it is not necessary to mention it because more stress is being put on Mr. Smith.
2) the student is being examined now?
" by them" has also been omitted here too because more stress is put on the student rather than the doer of the action.