It was in the Beihai Park ______they made a date for the first time ______the old couple told us their love story.
| A．that ,when | B．where, when | C．which, where | D．where ,that |
Since the Obama administration took office, the China—US relations ________ positive development thanks to joint efforts of both sides, President Hu said at the Nuclear Security Summit in Washington, April,12,2010.
| A．witnessed | B．were witnessed | C．had witnessed | D．have witnessed |
.The other day I was showing the boys the weekly chemistry experiment when, ________ I knew it, the mixture was bubbling over everywhere.
| A．if | B．before | C．though | D．unless |
It was not until all the milu deer ________ that we realized we should build a natural park to protect them.
| A．died off | B．died away | C．died out | D．died down |
Do you remember a certain occasion ________ you were in trouble and at that moment I gave you a hand.
| A．when | B．which | C．why | D．where |
You may catch up with others__________you work a little harder.
| A．so long as | B．so far as | C．however | D．unless |