"a person who seeks to correct social ills in an idealistic, but usually impractical or superficial, way," 1650s (as do-good), in "Zootomia, or Observations on the Present Manners of the English: Briefly Anatomizing the Living by the Dead. With An Usefull Detection of the Mountebanks of Both Sexes," written by Richard Whitlock, a medical doctor. Probably used even then with a taint of impractical idealism. Modern pejorative use seems to have begun on the socialist left, mocking those who were unwilling to take a hard line. OED has this citation, from "The Nation" in 1923:
There is nothing the matter with the United States except ... the parlor socialists, up-lifters, and do-goods.
The form do-gooder appears in American English from 1927, presumably because do-good was no longer felt as sufficiently noun-like. A slightly older word for this was goo-goo.
1. Look, you've typed " do " as'so " , and made nonsense of the whole sentence.
瞧, 你把do打成了so, 这样一来句子就不通了.
2. Beauty is an attitude. It has nothing to do with age.
3. The best thing to do when entering unknown territory is smile.
4. Failure is never quite so frightening as regret do.
5. For what do we live, but to make sport for our neighbours, and laugh at them in our turn?