Khan Academy
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.
www.khanacademy.org - 2020-09-15 - 收藏-
World English
English on the internet. The best online resource for English as a second or foreign language (ESL / EFL), English exercises and activities, online English lessons with native speakers of English.www.world-english.org
www.world-english.org - 2020-06-28 - 收藏 -
可汗学院Khan Academy
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.
cmn.khanacademy.org - 2020-05-21 - 收藏
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