It has been announced that candidates ______ remain in their seats until all the papers have been collected.
| A．can | B．will | C．may | D．shall |
The children，__________ had played the whole day long, were worn out.
| A．all of what | B．all of which |
| C．all of them | D．all of whom |
He wrote a letter __________ he explained what had happened in the accident.
| A．what | B．which |
| C．where | D．how |
She brought in her three friends, none of __________ I had ever met before.
| A．them | B．who |
| C．whom | D．these |
Ellen was a painter of birds and of nature，__________，for some reason, had withdrawn from all human society.
| A．which | B．who |
| C．where | D．whom |
The prize will go to the writer __________ story shows the most imagination.
| A．that | B．which |
| C．whose | D．what |