单项选择题
A．Social work. B．Applied physics. C．Medical care. D．Special education.
A．At a country school in Mexico. B．At a small American college. C．In a mountain valley of Spain. D．In a small village in Chile.
A．How animals survive harsh conditions in the wild. B．How animals alter colors to match their surroundings. C．How animals protect themselves against predators. D．How animals learn to disguise themselves effectively.