Holding down the Shift key while dragging restricts the created object. For example, instead of a rectangle you get a square, instead of an ellipse you get a circle. When you drag a handle of an existing object with Shift held down, the aspect ratio of the object is retained.
拖动时按住 Shift 键，将限制创建的对象。例如，您将得到一个正方形而不是矩形，得到一个圆形而不是椭圆。当您按住 Shift 键拖动现有对象的一个控点时，对象的纵横比保持不变。