Some embodiments include methods in which a pair of spaced-apart adjacent features is formed over a substrate. The features have silicon dioxide surfaces. Silicon nitride is deposited between the features. A first region of the silicon nitride is protected with a mask while a second region is not. The second region is removed to form an opening between the features. Some embodiments include semiconductor constructions that contain a pair of spaced-apart adjacent features. The features are lines extending along a first direction, and are spaced from one another by a trench. Alternating plugs and intervening materials are within the trench, with the plugs and intervening materials alternating along the first direction. The intervening materials consist of silicon nitride, and the plugs have lateral peripheries that directly contact silicon dioxide of the features, and that directly contact silicon nitride of the intervening regions.