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

Compounds Expand your vocabulary by studying more complex words built by the 'core words'.

HSK 2.0 (2010)	Big5	Gb	Pin	Eng
4		怀疑	huai2 yi2	to doubt/ to suspect/ doubt/ suspicion/ skeptical
6		疑惑	yi2 huo4	to doubt/ to distrust/ unconvincing/ to puzzle over/ misgivings/ suspicions