He was deep in thought with his eyes_____ on the ceiling.
---I feel terrible ,but I’ve just broken your ashtray.---_________, for I had meant to change it.
The great contributions he made______our country is_______worth remembering.
The theory _____ by Einstein was later to prove true, but at that time few people could accept it .
.Was it in 2000_________he was still in middle school_________this boy became an expert at computer?
Can you think of some cases________ drivers obviously knew the traffic rules but didn't obey them?