单项选择题
According to the scientific research, smoking is a major factor that _ to cancer.
单项选择题 Public interest centers on the __ of next week’s election, so it seems no one cares about the opening of this 20－storey shopping mall.
单项选择题 The factory has turned out more and better bicycles since the new techniques were __.
单项选择题 I would rather （）two weeks earlier.
