always(总是),usually(通常),frequently(经常) often (经常)sometimes(有时),seldom(不常),rarely(极少),never(从不) once(一次),twice(两次),等.
all the time 100%;
almost ,always 90%;
generally ,usually 80%;
often ,frequently 60-70%;
as often as not 40-50%;
sometimes ,at times 20-30%;
occasionally ,from time to time 10%;
hardly ,seldom ,rarely 5%;
never 0%.