改错：Tracing missing persons can take much patient detective work.

Tracing missing persons can take much patient detective work. But a special kind of “private eye” can trace the missing ancestors of whole peoples by studying the clues buried by words. __1__These philologists, such as the language detectives are called, have traced __2__the word trail back from peoples in Europe, India, South Africa, the Americas,and the Pacific islands in a tiny nameless, and forgotten tribe that roamed central __3__Eurasia 5000 to 6000 years ago, before the dawn of writing history. __4__Since a long time scholars have been puzzled over the striking __5__difference of words in different languages. In Dutch, vader; in Latin, pater;in __6__old Irish, athir; in Persian, pidar;in the Sanskrit of distant India, pitr.

These words all sounded likely and meant the same thing—“father” __7__Where did it happen that widely separated peoples used such __8__close related sound symbols？ The problem baffled linguists for years. The more so __9__because “father” was but one of a host of such coincidences. Towards the end of the 18 century it dawned on scholars that perhaps all these words stemmed __10__from some common language.