structural particle: used after a verb (or adjective as main verb), linking it to following phrase indicating effect, degree, possibility etc
to obtain
to acquire
to get
to gain
suit
proper
ready
finished
to be satisfied
to permit
to need to
to have gone as far as to
to have even done
can
(after a verb or adjective) one who (is) ...
(after a noun) person involved in ...
-er
-ist
(used after a number or 后hòu [后] or 前qián [前] to refer to sth mentioned previously)
(used after a term, to mark a pause before defining the term)
(old) (used at the end of a command)
(old) this
a surname
denoting a portion
this
these
yes, yes! (exclamation)