The migration of geese and other birds from north to south is one of the earliest signs that winter is on its way.
a form of communication between different types of animals
the movement of a group of animals or people from one place to another
different types of transportation used by humans
It is unknown whether Professor Boyle will return to teach this year or next. She is leaving the university indefinitely.
for a period of time without any decided end
without being certain of the right decision
for a very short period of time