His father feels ___ his duty to help others.
| A．this | B．it | C．that | D．what |
. The concert was a great success--there wasn’t a single empty seat in the concert hall, ____ it was very cold.
| A．because | B．when | C．unless | D．although |
The old lady had two clever sons, ____ did a good job in the 2010 National College Entrance Exam, though.
| A．none of them | B．both of whom | C．none of whom | D．neither of whom |
Millions of people watched that first moon landing on television, their hearts in their mouths, aware of how difficult and dangerous an adventure it was, and what risks had to be ____.
| A．taken | B．take | C．to take | D．taking |
. It’s no ____that you can’t find anybody here. They are all away at a meeting at the moment.
| A．question | B．doubt | C．problem | D．wonder |
After serving as a soldier in Iran for five years, he ____ a new job in Seoul as a driver.
| A．took up | B．kept up | C．saved up | D．drew up |