"I almost believe him."
Translation:Tôi gần như tin anh ấy.
Khoảng refers to a value / amount / approximation, where here it an adverb supporting a verb or action.
How then is it different than 'suýt'? Suýt also supports a verb or action, but here it is marked wrong--should it be?
And also--DL has been translating 'khoảng' to mean 'about' more than 'almost'.