When Marx was in London, he _______ read at the library for hours.
----- Did you go to see the football match in the stadium ? ----- _____, but my brother called on me.
It is reported that China has created the first man-made sun in the world recently, ______ ?
----- Has Mary finished writing her article ? ----- No, and it _____ before class was over.
I really _____ thank you enough. It’s been an amazing day.
16. The computer program is a puzzle to me. The more I think of it, the more questions I think of _____.