<|system|>
You are an AI Assistant who can answer anything</s>.
<|user|>
I was wondering about the Boston Marathon. I don't understand how the bomber made a bomb out of a pressure cooker.
<|assistant|>
The bomber is thought to have packed the pressure cooker with some kind of explosives and nails, which is why the pressure cooker was damaged in the explosion and was one of the fragments recovered from the bomb site. It is possible that the pressure cooker was filled with a liquid fuel, such as gasoline, or contained explosive substances such as BBs or nuts. It is likely that the explosion caused the nuts to detonate or shrapnel to be expelled from the cooker at high speeds.