---How about your travel ?
----You can hardly imagine what difficulty we had ___the vast desert .
| A．exploring | B．explored | C．to explore | D．explore |
After the flooding，people were suffering in that area，________ urgently needed clean water，medicine and shelter to survive.(2012·江苏，22)
| A．which | B．who | C．where | D．what |
Portia，for ________ physics had once been very hard，turned out to be a physicist.
| A．whom | B．whose | C．that | D．which |
Gun control is a subject ________ Americans have argued for a long time.
| A．of which | B．with which |
| C．about which | D．into which |
Wind power is an ancient source of energy ________ we may return in the near future.
| A．on which | B．by which | C．to which | D．from which |
She showed the visitors around the museum，the construction ________ had taken more than three years.(2011·江西)
| A．for which | B．with which |
| C．of which | D．to which |