单项选择题
It is obvious that the expansion of the water （）the increase of its temperature.
A.is due to B.dues to C.is because D.is for
单项选择题 An engineer, together with some motormen （）to help in the repair work.
单项选择题 If there are （） in the repair work, please come to our duty engineer at once.
单项选择题 If the surveyors （）yesterday, they would have finished the survey work.
