True

1. According to the AutoCAD for Design and Drafting documents1, a polyline is a connected sequence of line segments created as a single object. You can create straight line segments, arc segments, or a combination of the two2341. Therefore, the correct answer is True. A polyline can include both straight line segments and arc segments.

2. False.According to the AutoCAD for Design and Drafting documents1, a spline is a smooth curve that passes through or near a set of fit points, or that is defined by the vertices in a control frame. A spline does not have a constant radius, but rather a local radius at each point on the curve2. Therefore, AutoCAD cannot directly dimension or display a radius of a spline curve23. You can use some workarounds such as exploding the curve to arc segments with the FLATTEN command2, or creating a polyline over the top with arc active3, but these may not be accurate or desirable. Therefore, the correct answer is False. The radius on a spline cannot be found in AutoCAD properties.3. TrueAccording to the AutoCAD for Design and Drafting documents1, a 2D polyline is a connected sequence of line segments created as a single object. You can specify an elevation for a 2D polyline using the Edit Polyline Elevations command2. However, this command will assign the same elevation to all vertices of the polyline2. Therefore, you cannot assign different elevations to different segments or points of a 2D polyline. Therefore, the correct answer is True. You can assign only one elevation to a 2D polyline.