21. Look over there—there’ s a very long, winding path _________ up to the house.
A. leading B. leads C. led D. to lead
22. — Did Alan enjoy seeing his old friend yesterday?
— Yes, he did. He ______ his old friend for a long time.
A. didn’t see B. hadn’t seen C. hasn’t seen D. wouldn’t see
23．_____ alone in the large house, the little boy had to learn to survive by himself.
A. To leave B. Leaving C. Left D. Being left
