These words LINK the subject to words in the predicate.

 

Mrs. Gordon is a teacher.

 

The man was lost.

 

It seems very cold outside today.

 

am

is

are

was

were

will be

become (s)

became

seem (s)

appear (s)

look (s)

taste (s)

sound (s)

grows (s)

smell (s)

feel (s)