If Newton lived today, he would be surprised by what _______ in science and technology.
| A．had discovered | B．had been discovered |
| C．has discovered | D．has been discovered |
______ chemistry is a branch of chemistry．
| A．Applying | B．Apply | C．Applied | D．To apply |
More and more high-rise buildings have been built in big cities ______ space．
| A．in search of | B．in place of |
| C．for lack of | D．for fear of |
---We haven’t seen each other for ages．
---No, I don’t remember how many years ago _______ I last saw you．
| A．it was that | B．was it that |
| C．it was when | D．was it when |
We are still at the airport．If it weren’t for the delayed flight, we _______ the concert right now．
| A．can be enjoying | B．must have enjoyed |
| C．would be enjoying | D．should have enjoyed |
_____ his research paper, Professor Reagan experienced various hardships and loneliness for nearly half a year．
| A．Accomplishing | B．To accomplish |
| C．Accomplished | D．Having accomplished |