【单选题】

In every cultivated language there are two great classes of words, which makes up the whole vocabulary. First, there are those words (56) which we become familiar in daily conversation, which we (57) , that is to say, from the (58) of our own family and from our friends, and (59) we should know and use (60) we could not read or write. They (61) the common things of life with all the people who (62) the language. Such words may be called "popular", since they belong to the people (63) and are not excluded (64) a limited class.

On the other hand, our language (65) a large number of words which are comparatively (66) used in ordinary conversation. Their meanings are known to every educated person, but there is little (67) to use them at home or in the market-place. Our (68) acquaintance (熟悉) with them comes not from our mothers’ (69) or from the talk of our schoolmates, (70) from books that we read, lectures that we (71) , or the more (72) conversation of highly educated speakers who are discussing some particular (73) in a style properly higher above the habitual (74) of everyday life. Such words are called "learned", and the (75) between them and the "popular" words is of great importance to a right understanding of language study process.
A、border
B、link
C、degree
D、extent