Fireworks, ________ of gun powder or flash powder _______ in a tight paper tube, make the big flash or boom effect.
Try she might, Sue couldn’t get the door open.(2011 .全国I) A. if B when C. since D. as
--- Is everyone here? --- Not yet … Look, there the rest of our guests! (2010 … 江苏)
We laugh at jokes, but seldom about how they work. (2010 .四川)
Only when he apologizes for his rudeness to him again.(2013.江西)
Not once to Michael that he could one day become a top student in his class. (2013 .湖南)