Task: Question Answering
Input (English): Background Paragraph: Geologists study earthquake waves to “see” Earth's interior. Waves of energy radiate out from an earthquake’s focus. These waves are called seismic waves ( Figure below ). Seismic waves go different speeds through different materials. They change speed when they go from one type of material to another. This causes them to bend. Some seismic waves do not travel through liquids or gases. They just stop. Scientists use information from seismic waves to understand what makes up the Earth’s interior. 
Story: Mary is studying the seismic waves of a recent earthquake from 2 locations around its focus. She notes at point A the waves are easily detectable. at point B the waves are unable to be read at all, as if they just stopped. 
Question: Given Mary decides to check the readings for two other locations, points C and D, and notices the waves at D are slower, will the areas underground at points C and D be made of the same materials or different materials?
Output (English): different.