----- 机械工程教材
TO be Of the greatest benefit, the Keys should be used sparingly. They should be used much in the same manner as a pupil would go to a teacher for instruction with regard to answering some example he was unable to solve. If used in this manner, the Keys will be of great help and assist ance to the student, and will be a source of encouragement to him in studying the various papers composing the Course.
{{comment.content}}