| 词源 |
plain sailing. In technical nautical language plane sailing means determining a ship’s position on the assumption that the earth is flat and the ship is on a plane; this is a simple, straight- forward method of computing distance. But in the 19th century, the words entered general use as an expression meaning “per- fectly straightforward action, a course of action that there need be no hesitation about.” The word plane came to be spelled plain and has remained that way ever since. |