Most prompts ask you to select just one object from the current viewport. However, some tasks allow you to select one or more objects; for example, the Set toolset allows you to select several objects of the same type and group them into sets. You can select multiple objects using the [Shift]+Click method described in “Selecting and unselecting individual objects,” Section 6.2.1. An additional method for selecting multiple objects is to drag a rectangle around those objects. You might find it useful to use the selection option tools to adjust the shape of the drag-select region. You can also choose which objects are selected by the drag-select region. To access the selection option tools, click 
in the prompt area. For more information, see “Modifying the shape of the drag-select region,” Section 6.3.5, and “Choosing which objects are selected by the drag-select region,” Section 6.3.6.
To drag-select multiple objects:
Imagine a rectangle that encloses only the objects you want to select.
Click at one corner of the rectangle and, while continuing to press the mouse button, drag until you have enclosed all the objects.
Release the mouse button.
All the valid objects inside or crossing the rectangle are highlighted.
Click mouse button 2 to indicate that you have finished selecting objects.
Sometimes it is convenient to use a combination of the [Shift]+Click and drag-select selection techniques. For more information, see “Combining selection techniques,” Section 6.2.4.
Tip: If you select multiple objects and then want to unselect one or more of them, [Ctrl]+Click the objects you want to unselect. To unselect all the objects, click in an unused area of the viewport.
