单选题 Softening point of petroleum asphalt The height at which the steel ball sinks is ( ).

单选题 When measuring mechanical impurities in oil products, use the precision requirements of the analytical balance ( ).

单选题 GB/ T511-88 "Method for Determination of Mechanical Impurities in Petroleum Products and Additives" the filter paper specification for use is ( ).

单选题 To measure the mechanical impurities of an oil whose 100 ℃ viscosity is less than 20 mm2/s, it is necessary to weigh the ( ) sample for experiment.

单选题 The higher the softening point of petroleum asphalt, ( ).

单选题 The ( ) of petroleum asphalt has nothing to do with its softening point.

单选题 When measuring mechanical impurities in the oil product, dry the filter paper with precipitation in the oven for no less than 1 h, and then place it in the dryer to cool ( ).

单选题 The thermometer used to determine the softening point of asphalt has a measuring range of 30 to 180 ℃, and its minimum division value should be ( ).