Final answer:
To resolve the problem of a blood smear being too long, a thin film of blood with a 'feathered edge' should be created on a glass slide. This will ensure a single layer of cells that can be easily observed under a microscope.
Step-by-step explanation:
If a blood smear is too long, the problem can be resolved by making a very thin film of blood with a 'feathered edge' on a glass slide. This will create a single layer of cells that can be easily observed under a microscope. By creating a thin smear, the cells will be spread out and visible, allowing for accurate analysis and counting of different types of blood cells.