for long
From Longman Dictionary of Contemporary Englishfor longfor long[usually in questions and negatives] for a long time Have you known them for long? I haven’t seen her for so long that I’ve forgotten what she looks like. → longExamples from the Corpusfor long• Have you been working here for long?• Have you known the Garretts for very long?• He'll have to stay in hospital, but not for long.• I haven't known them for very long.• I hope his speech doesn't go on for long.