Scientists have found no ________of life on Mars so far,though great efforts have made on the research.
| A．symbols | B．signs | C．marks | D．signals |
Gun control is a subject __________ Americans haveargued for a long time.
| A．of which | B．with which | C．about which | D．into which |
—Can you believe I had to pay 30 dollars for a haircut? — You should try the barber's __________ I go. It's only 15.
| A．as | B．which | C．where | D．that |
Occasions are quite rare __________ I have the time tospend a day with my kids.
| A．who | B．which | C．why | D．when |
It was April 29，2011 __________ Prince William andKate Middleton walked into the palace hall of the wedding ceremony.
| A．that | B．when | C．since | D．before |
A bank is the place __________ they lend you an umbrella in fair weather and ask for it back when it begins to rain.
| A．when | B．that | C．where | D．there |