In a passive loudspeaker system the low-level audio signal is first amplified by an external power amplifier before being sent to the loudspeaker where the signal is split by a passive crossover into the appropriate frequency ranges before being sent to the individual drivers.
A landform is a natural feature of the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography.
For example, the oceans are a landform of water. Over 70% of the earth's surface is ocean. A lake landform is a body of water surrounded by land. To keep things straight, you usually refer to a landform along with what type of landform it is - a lake landform, an ocean landform, a mountain landform, a desert landform.