Use a thermometer to judge whether it is cold or hot.

(1) Thermometer works by using the property that liquid expands when heated and contracts when cooled. Mercury, kerosene and alcohol can be used as temperature measuring liquids.

(2) According to the calibration characteristics of the thermometer, it is known that the thermometer is A, so the measurement range covers the possible temperature values of the human body;

(3) As can be seen from the figure, thermometer A is a thermometer with a scale value of 0. 1℃, so it is 38.5℃;

The temperature displayed on thermometer B is lower than 0℃, the scale value is 1℃, and the indicator is -5℃.

So the answer is: (1) thermal expansion and cold contraction; Alcohol;

(2) A; The measuring range covers the possible temperature values of the human body;

(3)38.5; -5.