Answer:
Beakers should not be used for measuring a liquid's volume because beakers can be inaccurate. For example, they are typically accurate within 5 percent. Beakers should only be used for approximating volume.
A better choice for accurate volume would be a graduated cylinder, since they are accurate within 1 percent. The best options are pipets, burets and volumetric flasks. All three are accurate within less than 0.2%.
Essentially, beakers are not precise, and therefore should not be used for measuring the volume of a liquid.