Complex sentence: A police car that had been behind it gave chase and the two cars careened through the narrow streets at seventy miles and hour, until finally the Ford hit a lamppost, skidded onto the sidewalk and flipped over.
Split into simpler sentences: A police car that had been behind it gave chase. The two cars careened through the narrow streets at seventy miles and hour, until finally the Ford hit a lamppost, skidded onto the sidewalk and flipped over.