A．To explain that dogs' brain are more complex than crocodiles'.
B．To point out that crocodiles can communicate with dogs.
C．To give an example of animals that care for their young.
D．To emphasize that crocodiles have highly developed brains.
A．Its relatives answer back.
B．The mother repeats the call.
C．The rest of its family waits near water.
D．The mother calls to other adult crocodiles for assistance.
A．To remind students of information from a previous lecture.
B．To point out a feature common to all desert plants.
C．To reinforce a point about drought-tolerant plants.
D．To help students understand the concept of adaptation.