Provide the dimensions of the bounding box that contains the keyboard that was spotted in image no. 3.
dimensions of the bounding box refers to (W, H); keyboard refers to OBJ_CLASS = 'keyboard'; image no. 3 refers to IMG_ID = 3
SELECT T1.W, T1.H FROM IMG_OBJ AS T1 INNER JOIN OBJ_CLASSES AS T2 ON T1.OBJ_CLASS_ID = T2.OBJ_CLASS_ID WHERE T1.IMG_ID = 3 AND T2.OBJ_CLASS = 'keyboard'