28. You can’t complain of being lonely____you don’t make any effort to communicate with others.
| A．when | B．until | C．unless | D．Once |
After graduating from college, I took some time off to go travelling, __________ turned out to be a wise decision.
| A．that | B．which | C．when | D．where |
My grandfather is fond of talking about the good old days, __________ is often the case with old people.
| A．when | B．as | C．that | D．what |
Marco was lucky enough to meet another prisoner __________ enjoyed listening to his stories.
| A．who | B．which | C．whose | D．what |
The motorcycle competition in the desert, __________ lasted ten days, is over now.
| A．where | B．it | C．that | D．which |
Li Ming got high marks in the exam, __________ surprised his classmates.
| A．when | B．that | C．which | D．who |