单项选择题
It is important to use only pure lead and to choose a thickness of wire which is greater than the normal allowable clearance but （） this amount.
A.not less than twice B.greater at least twice than C.not greater twice than D.larger three times than
单项选择题 It is important that the water （） very often as this can lead to increased deposits.
单项选择题 It is abnormal that when the engine is being turned by the turning gear or by hand, （）.
单项选择题 Increasing the temperature of a fuel will reduce its （）.
