The medical reform in that country proved to be _____ failure, but as we know, success often comes after _____ failure.
| A．a; the | B．a; / | C．a; a | D．/; / |
31．— I'm wondering why the visitors chose to stay with the host family．
— _____real local life．
| A．Experiencing | B．Experience | C．To experience | D．Having experienced |
30．How long do you think it will be _____ we can find a new water source?
| A．after | B．before | C．when | D．Since |
29．High up in the mountains _____ a quiet small village, with only 20 households．
| A．surrounds | B．locates | C．lies | D．Lays |
28．A heavy snow promises a good harvest, _____ is often the case．
| A．where | B．as | C．that | D．What |
27．After his wife died, he kept himself _____ from other people and the outside world,
| A．set off | B．cut off | C．put off | D．taken off |