时间点（确定）points of time (definite)
now
then
today
tomorrow
tonight
yesterday
频率（确定）frequency (definite)
annually
daily
fortnightly
hourly
monthly
nightly
quarterly
weekly
yearly
The word bimonthly is ambiguous and best avoided. Bimonthly can mean "twice a month" or "every two months". The same is true of biyearly and biannually.
频率（不定）frequency (indefinite)
always
constantly
ever
frequently
generally
infrequently
never
normally
occasionally
often
rarely
regularly
seldom
sometimes
regularly
usually
时间关系（不确定）relationships in time (indefinite)
already
before
early
earlier
eventually
finally
first
formerly
just
last
late
later
lately
next
previously
recently
since
soon
still
yet
