单项选择题
Every precaution must be taken to avoid （）.
A.sparking being taking place B.to spark taking place C.sparking to be taken place D.sparking taking place
单项选择题 It is obvious that the expansion of the water （）the increase of its temperature.
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.
