What is the image ID with a predicted class of "parked on"?
predicted class of "parked on" refers to PRED_CLASS = 'parked on';
SELECT DISTINCT T1.IMG_ID FROM IMG_REL AS T1 INNER JOIN PRED_CLASSES AS T2 ON T1.PRED_CLASS_ID = T2.PRED_CLASS_ID WHERE T2.PRED_CLASS = 'parked on'