Every man is not polite, and all are not born gentlemen.
38. may as well notas结构，此结构可译为与其不如不。
One may as well not know a thing at all as know it but imperfectly.
39. have only to do结构，此结构表示只须就能的意思。
We have only to turn to that extraordinary discovery made by Edison to see the significance of it.
40. not unless句型
No increase in output can be expected unless a new assembly line is installed.
41. betterthan句型
Better my life should be ended by their hate, than that hated life should be prolonged to live without your love.
42. as it were是一个非常常用的插入语，意思是好象，可以说等。
Apiece of iron near a magnet, though apparently separate from it , feels, as it were, the threads of this attachment.