.The development of industry has been________gradual process throughout________human existence,from stone tools to modern technology. (2012·浙江,2)
At the age of twenty Steve left his hometown, _____ to return without making his mark.
Reportedly, yesterday a group of American soldiers were walking along the road in Iraq when a bomb was _______, three of whom were killed.
Seeing her father come back, ______________.
I feel it is you who ________ for the accident.
I can’t remember ________ made the teacher give Mary the permission to leave the class earlier.