The water tank of the WC began to drip from the holes where the tank is attached to the toilet bowl. I changed the screws with their respective gaskets, put silicone around the head of the screw inside the water tank but it still leaks.

An old trick It is the car, remove the PVC toad, and clean it that scale makes a bad seal when you pull the lever the water comes out because the scale creates a slight shoe on the toad and you have to give the impression that it drips, just cleaning with soap and ready

Finally I changed the set of screws and cup-tank junction gasket. The original screws are plastic and I put similar ones. I found in Home Depot a kit with the screws and the gasket and holy solution. I learned two things: 1.- If the connection to the water hose does not interfere and does not represent any problem, do not remove it. I say it because I had no problem with the hose, however I removed it and in the end I solved the original problem and the connection of this hose began to have a small leak. 2.- Press without tool. The first time, I changed the plastic screws for steel ones because they didn't have them in the plastic hardware store and the clerk told me they were better. It was not so. When placing the plastic ones I squeezed them with my hand and it looked very good. The water hose had been tightened with a tool first and had a small leak, I removed it, squeezed it with my hand and it looked good. Ah! and I didn't have to use silicone ... I appreciate the recommendations, Regards!