Ellen was a painter of birds and of nature，________，for some reason，had withdrawn from all human society.(2012·浙江，17)
A．which B．who C．where D．whom
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
(2009·陕西)Gun control is a subject ________ Americans have argued for a long time.
A．of which B．with which
C．about which D．into which
(2010·上海)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
