Slurry, polishing fluid set, polishing fluid, and substrate polishing method using same

A method of inhibiting reduction in a polishing rate, comprising:

• adjusting light transmittance produced by abrasive grains including tetravalent cerium hydroxide particles to at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %;
• and
• polishing at least a portion of a film to be polished while supplying a polishing liquid comprising the abrasive grains and an additive between an abrasive pad and the film to be polished.

A method of adjusting a polishing rate of a slurry comprising water and abrasive grains including tetravalent cerium hydroxide particles, the method comprising:

• adjusting light transmittance produced by the abrasive grains to at least 50%/cm for light with a wavelength of 500 nm in an aqueous dispersion with a content of the abrasive grains adjusted to 1.0 mass %.