— Have you ever visited the Opera House?
—Yes．When I was in Sydney, I ______ it twice．
| A．have visited | B．visited |
| C．had visited | D．would visit |
After visiting Harbin, most of the foreign friends said they would never forget the time ________ they had spent.
| A．that | B．what |
| C．when | D．at which |
My favorite writer is Mo Yan, some of ________ novels have a surprising ending.
| A．whom | B．his |
| C．whose | D．which |
A lot of lovers chose to get married on Dec. 12, 2012, ________ the date, the month and the year match.
| A．that | B．on which |
| C．in which | D．which |
I felt surprised that anyone of his intelligence ________ such an easy test.
| A．might have failed | B．could have failed |
| C．should have failed | D．must have failed |
We ________ take clean drinking water for granted. One day we may run out of it.
| A．needn't | B．can't |
| C．won't | D．shouldn't |