1. Simple optical microscope. One lens.
Disadvantage: Only Van Leeuwenhoek made them, and he's dead.
Advantage: Worked pretty well. With them, Van Leeuwenhoek discovered protozoa and bacteria.
2. Compound optical microscope. Has both an ocular and objective lens.
Disadvantage: limited resolution. Can resolve bacteria, but not smaller things like viruses.
Advantage: can be used with live specimens (using phase contrast or polarized or other special illumination).
3. Binocular dissecting microscope (optic). Has a pair of ocular and objective lenses, and supposedly presents a "3D" view of the specimen to the viewer (I was never able to see in 3D using these darn things).
Disadvantage: Limited magnification
Advantage: Can be used to perform surgery on small but not microscopic specimens, such as fruit flies. Is used in "microsurgery" in hospitals too.
Hope this helps buddy!
Answer:
Cultivate prime grain and with timely care
Green algae is a representative of sponges
