According to the passage, when a sick frog is near ones without the disease, it turns out that they.
The word "squirmed away" can be replaced by.
After reading the whole passage, we know that "quarantine" means.
We can conclude that the experiment mentioned in the passage could.
Conclude the hypothesis that has been doubtful since the ancient time.
help the biologists and ecologists to find the solution to cure sick tadpoles.
enlighten the researchers about the response of some animals to the illness.
answer why some species infect some diseases but some do not.