The police say radio signals were probably used to set the bomb __________.
| A．about | B．down | C．off | D．out |
I ________ with my grandma because my parents have gone abroad for further study.
| A．stayed | B．am staying | C．have stayed | D．was staying |
How can they learn much ________ they spend so much time playing computer games?
| A．although | B．when | C．till | D．until |
Cars do cause us some health problems, in fact, far more serious ________ than mobile phones do.
| A．one | B．ones | C．it | D．those |
After ________, the litter girl was depressed and kept silent all the day.
| A．being made fun | B．making fun of |
| C．making fun | D．being made fun of |
The scientist corresponds with colleagues in order to learn about matters ________ to her own research.
| A．relevant | B．instant | C．resistant | D．important |