to作介词时，后面接动词－ing形式或是地点名词，to还可用于see to和come to等短语动词中，它还与某些带双宾语的动词连用，以引出第二个宾语。例句：Give the book to Tom.I am looking forward to seeing you.
常用短语
according to
air-to-air
air-to-surface
as to
call to quarters
due to
how-to
lean-to
made-to-order
man-to-man
mouth-to-mouth resuscitation
nine-to-fiver
one-to-one
owing to
person-to-person
portal-to-portal
previous to
prior to