A grand celebration along with the military parade was broadcast live at 11 am, ____

21. A grand celebration along with the military parade was broadcast live at 11 am, _____ millions of families were sitting in front of the television, watching it.
A. which B. when C. what D. that
22. When we Chinese need help in a foreign land, at our back __________ a strong motherland.

1. will stand B. stands C. is standing    D. stood

23. When I am faced with any illegal behavior, my_______ will not allow me to sit there in silence.

1. conscience B. assessment C. dilemma D. privilege

24. The scientist found a cure for the disease,  approximately 600 clinical cases.

1. studying B. to study C. having studied D. to have studied

25. New employees _________ they are skilled, will get more opportunities for personal development.

1. though B. since C. once D. unless

答案21-25 BBACC