What is so small it can be seen only with an electron microscope?
all invertebrates humans bacteria alveoli acetic acid orchids smallpox planets
A B C D E F G H
Some smallpox viruses are maintained in laboratories.
smallpox is so small that it can be seen only with an electron microscope
What is so small it can be seen only with an electron microscope? (A) all invertebrates (B) humans (C) bacteria (D) alveoli (E) acetic acid (F) orchids (G) smallpox (H) planets