( plumb lines)
A plumb line is a piece of string with a weight attached to the end that is used to check that something such as a wall is vertical or that it slopes at the correct angle.
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( plumb lines)
A plumb line is a piece of string with a weight attached to the end that is used to check that something such as a wall is vertical or that it slopes at the correct angle.
N-COUNT
Collins COBUILD Advanced Learner's English Dictionary. Английский словарь Коллинз COBUILD для изучающих язык на продвинутом уровне. 2006