A spirit level can be used __________.

A spirit level is a tool used to determine whether a surface is perfectly level (horizontal) or plumb (vertical). The design of a spirit level includes a sealed tube filled with liquid and an air bubble. When the level is laid on a surface, the position of the bubble indicates whether the surface is level or upright.

Using the spirit level in both vertical and horizontal positions allows for versatile applications in construction, carpentry, and various maintenance tasks. This dual functionality is essential for ensuring the accuracy of installations, such as shelves, pictures, doors, and windows, where both orientations may need to be checked.

While the other options suggest limitations on the spirit level's usage, the correct answer reflects its true capability, providing an efficient means to achieve precision across multiple projects.