Abstract: In the 20th century, science and technology on the human contribution to one of the most important is to liberate from the heavy manual labor people have plenty of leisure time.

• 摘要：20世纪科学技术对揉做出的最重要贡献之一，是将揉从繁重的体力劳动中解放出来，使人有了充裕的休闲时间。