I disagree that "certain" can mean "not explicitly". While "certain" can have multiple meanings, the context will usually tell you what is meant and the same is true of "apart from". Apart from basketball, he (also) plays football.
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ocsenttdd:I think in this sentence 'certain' means not explicitly:e.g: he raised certain personal problems with mehttp://www.thefreedictionary.com/certain (meaning 6a)