How can I know my blood type?

Basically, we use the kind of needle we often see to prick the ring finger (it is estimated that the ring finger is tender and easy to prick), and of course, we will wipe the finger with alcohol cotton before pricking. After binding, suck out some blood with a straw. Yeah, it seems that this step varies from person to person. Some people want the doctor to squeeze the blood out of their fingers. Some people come out without touching blood at all. It looks terrible. However, it should be normal to see a doctor in both cases. Then the blood sucked out will drip into two grooves that have been filled with professional potion (the potion seems to be yellow-green, I can't remember clearly). Then you can know your blood type immediately:

If the blood in both grooves is dissolved in the liquid medicine, it is O-type blood.

If the blood in the two grooves does not dissolve in the liquid medicine, it is AB blood.

If the blood in the first groove does not dissolve and the blood in the second groove dissolves, it is type A blood.

If the blood in the first groove is dissolved and the blood in the second groove is not dissolved, it is type B blood.