As shown in the figure, AB is a long metal rod resting on a bracket, and the B end is fixed; The A end is connected to the lower end of the pointer, and the pointer can rotate around 0: 00. This forms a solid thermometer, which works by using the principle that solids expand when heated and contract when cooled. When the temperature rises, the pointer will be biased to the right (fill in "left" or "right").

Solution:

It is known that AB is a long metal rod resting on a bracket, and its B end is fixed. When the temperature rises, the length of AB will increase and extend to the left, driving the pointer to deflect to the right. On the contrary, the temperature decreases, the length of AB decreases, and the pointer deflects to the left, so the principle of solid expanding with heat and contracting with cold is used.

So the answer is: solid expands when heated and contracts when cooled; That's right.