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

☆ CONCERN; WORRY sự lo lắng
HSK 3.0 11000 CHINESE WORDS
7 惦记  diànji to think of, to keep thinking about, to be concerned about

ENGLISH 6000 THEME WORDS

OXFORD 5000 CORE WORDS

TANAKA 6000 CORE WORDS