By careful observation and precise calculation, Nicolaus Copernicus _____ that there is no one center in the universe and the sun is the center of the solar system.
| A．believed | B．thought | C．concluded | D．imagined |
several time, the young scientist still kept on making his experiments.
| A．Having been failed |
| B．Having failed |
| C．Though failed |
| D．Because of failure |
--- Lucy doesn’t seem to be what she was.
--- No.so much in the war has made her more thoughtful.
| A．Seen |
| B．Her seeing |
| C．Having seen |
| D．To have seen |
--- What do you suppose made her worried?
--- a gold ring.
| A．Lose |
| B．Lost |
| C．Losing |
| D．Because of losing |
--- The English exam is not difficult, is it?
--- . Even Tom to the top students failed in it.
| A．Yes; belongs |
| B．No; belonged |
| C．Yes; belonging |
| D．No; belonging |
--- Hi, Mary. Would you like to go to the concert this evening?
--- Sorry, Tom. tomorrow’s lessons, I have no time to go out with you.
| A．Not preparing |
| B．Not having prepared |
| C．Not to prepare |
| D．Being not prepared |