_ _ is well-known to all that the 2016 Olympic Games will be held in Rio de Janeiro ,Brazil.
| A．As | B．What | C．That | D．It |
The days are gone ________ physical strength was all you needed to make a living.(2011·天津，10)
| A．when | B．that | C．where | D．which |
Ellen was a painter of birds and of nature，________，for some reason，had withdrawn from all human society.(2012·浙江，17)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 |
Gun control is a subject ________ Americans have argued for a long time.
| A．of which | B．with which |
| C．about which | D．into which |