1 (wiktionary) 2 (vi.wikipedia) 3 (en.wikipedia) 4 (glosbe)

Compounds Expand your vocabulary by studying more complex words built by the 'core words'.
Etymology Explore the origin of the 'core words'.
Wordsense Learn about the wordsenses of the english term.

TOPIK 11000 KOREAN WORDS

☆☆☆ STUDYING IN ADVANCE sự luyện tập trước học bài trước
HSK 3.0 11000 CHINESE WORDS
3 预习  yùxí to prepare a lesson

ENGLISH 6000 THEME WORDS

OXFORD 5000 CORE WORDS

TANAKA 6000 CORE WORDS