People thinking about the origin of language for the first time usually arrive at the conc

lusion that it developed gradually as a system of grunts, hisses and cries and【51】 a very simple affair in the beginning.【52】, when we observe the language behaviour of【53】 we regard as primitive cultures, we find it【54】 complicated. It was believed that an Eskimo must have the tip of his tongue a vocabulary of more than 10,000 words【55】 to get along reasonably well, much larger than the active vocabulary of an average businessman who speaks English.【56】, these Eskimo words are far more highly infleeted (词尾变化) than【57】 of any of the well-known European languages ,for a【58】 noun can be spoken or written in【59】 hundred different forms, each【60】 a precise meaning different from that of any other.

The forms of the verbs are even more【61】 . The Eskimo language is, therefore, one of the most difficult in the world to learn,【62】 the result that almost no traders or explorers have【63】 tried to learn it. Consequently , there has grown up, in communication between Eskimos and whites, a jargon【64】 to the pidgin English used in Old China, with a vocabulary of from 300 to 600 uninflected words. Most of them are derived from Eskimo but some are derived from English, Danish, Spanish, Hawaiian and other languages. It is this jargon that is usually【65】 by travellers as "the Eskimo language".

(51)

A．must be

B．must have been

C．ought to be

D．should be