Only era can vary in length of time.Era means age,period which doesn't exactly define the time
Century=100 years
decade=10 years
millennium = 1000 years,
President who resigned during the fall of saigon was President Nixon
To remove preconceived notions and ideas from one's mind before writing is to be unprejudiced.
If you don't have any prejudice towards the topic you are talking about, means to be completely objective and not to show any personal feelings about the said topic.
