【单选题】
If we were asked exactly what we were doing a year ago， we should probably have to say that we could not remember.But if we had kept a book and written in it an account of _31_ each day， we should be able to give an answer _32_ the question.
It is the same in the history. _33_ have been forgotten because we do not have any written account of them. Sometimes men _34_ a record of the important happenings in _35_ country， _36_ often it was destroyed by fire or in a war. Sometimes there was never any written record at all because the people _37_ did not know how to write. For example， we know _38_ the people who lived inChina 4，000 years ago， because they could write and _39_ written records for these who live _40_ them.But we know _41_ nothing about the people who lived even 200 years ago inCentralAfrica， because they _42_.
Sometimes， of course， even if the people cannot write， they may know something of the past. They have learned about it from _43_ people， and often songs and dances and stories have been made about the most important happenings， and these have been sung and acted and told _44_ many generations (後代)。 Most people are proud to tell _45_ their fathers did in the past. This we may call “remembered history”。 _46_ has now been written down. It is not so exact _47_ so valuable to us _48_ written history is， because words are much more easily _49_ when used again and again in speech than copied in writing.But _50_ no written records， such spoken stories are often very helpful.