مَا دَامَ links one statement to the time during which another state continues.
أَنَا قَائِمٌ مَا دَامَ الْمُعَلِّمُ قَائِمًا
I remain standing as long as the teacher remains standing.
Inside the مَا دَامَ clause:
- الْمُعَلِّمُ is the marfu ism.
- قَائِمًا is the mansub khabar.
Do not confuse the earlier قَائِمٌ with this khabar; it belongs to the main statement.