多邻国美股盘前涨超20%

Group 1 - The core viewpoint of the article highlights that Duolingo's stock surged over 20% in pre-market trading due to strong user growth and an upward revision of revenue guidance for the year [1] - The company reported that its daily active users reached 47.7 million in the second quarter, representing a significant year-over-year increase of 40% [1] - Duolingo has raised its full-year revenue guidance, indicating positive expectations for future financial performance [1]