有质量相等的实心铁块和木块分别放入两个完全相同置于水平桌面上的容器中，然后分别将两个容器加满水，两物体静止后，比较两物体受到浮力F_铁与F_木、两容器底受到液体的压强p_铁底与P_木底的关系是（　　）

A．F_铁＞F_木、p_铁底＞p_木底

B．F_铁＜F_木、p_铁底=p_木底

C．F_铁＞F_木、p_铁底=p_木底

D．F_铁＜F_木、p_铁底=p_木底

In every cultivated language there are two great classes of words which, taken together, comprises the whole vocabulary. First, there are those words (1) which we become acquainted in daily conversation, which we (2) , that is to say, from the (3) of our own family and from our familiar associates, and (4) we should know and use (5) we could not read or write. They (6) the common things of life, and are the stock in trade of all who (7) the language. Such words may be called "popular", since they belong to the people (8) and are not the exclusive (9) of a limited class.

On the other hand, our language (10) a multitude of words which are comparatively (11) used in ordinary conversation. Their meanings are known to every educated person, but there is little (12) to use them at home or in the market-place. Our (13) acquaintance with them comes not from our mother’s (14) or from the talk of our school-mates, (15) from books that we read, lectures that we (16) , or the more (17) conversation of highly educated speakers who are discussing some particular (18) in a style appropriately elevated above the habitual (19) of everyday life. Such words are called "learned", and the (20) between them and the "popular" words is of great importance to a right understanding of linguistic process.

13（）

A.primary

B.first

C.principal

D.prior