---- Is Mary coming to the concert? ---- I think ________.
It was in the room _________ he was born _________ the meeting was held.
More than 10,000 competitors from the world came to Beijing to compete __________ each other __________medals in 2008
Some scientists believe that ________ is no doubt ________ a cure for AIDS will be found.
The teacher asked his students to leave a space in their exercise books ________.
The driver who died in the accident _________, but he didn’t wear the seat belt.A. could survived B. could have survivedB. must survived D. must have survived