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
to speak
to say
to explain
to scold
to tell off
a theory (usually in compounds such as 日心说 heliocentric theory)
to criticize
to try to influence someone to do something
to mean