1. The study of custom can be profitable only after certain preliminary propositions have been accepted, and some of these propositions have been violently opposed.
    只有在某些基本的主张被接受下来、同时有些主张被激烈反对时，对风俗的研究才是全面的，才会有收获。

2. And it spread to Britain where wild rabbits are regarded as a pest but where domesticated rabbits, equally susceptible to the disease, are the basis of a profitable fur industry.
    这种疾病又蔓延到了英国。在英国，野兔被当作有害的动物，可是家兔是赚钱的毛皮工业的基础，然而家兔同样易感染这种疾病。

3. It´s more profitable to import flour.
    进口面粉可以获得更多利润。