In every cultivated language there are two great classes of words which, taken together, comprise the whole vocabulary. First, there are those words（1）which we become acquainted in daily conversation, which we learn, that is to say, from the（2）of our own family and from our familiar associates, and which we should know and use（3）we could not read or write. They concern the common things of life, and are the stock in trade（惯用手段） of all who（4）the language. Such words may be called "popular", since they belong to the people（5）and are not the exclusive right of a limited class.
（6）, our language comprises a multitude of words which are comparatively seldom used in ordinary conversation. Their meanings（7）to every educated person, but there is little necessity to use them at home or in the market-place. Our first（8）with them comes not from our mother's lips or from the talk of our school-mates, but from books that we read, lectures that we listen to, or the more formal conversation of（9）educated speakers who are discussing some particular topic in a style appropriately elevated above the habitual level of everyday life. Such words are called "learned", and the（10）between them and "popular" words is of great importance to a right understanding of linguistic process.
（5）下列正确的是（ ）

A.at least

B.at most

C.at large

D.at best