Question

When I entered the room, I found a little boy _____ on his mother’s knees _____ to draw a picture.

1. A.
   seated; learning
2. B.
   sitting; to learn
3. C.
   seating; learning
4. D.
   sat; was learning

Answer 1

A
seat是及物动词，后没有宾语， 故此处用过去分词做后置定语 表示“坐在……”a little boy 是learn的执行者所以用learning。