ABC Partners, Ltd. (ABC Partners), a limited partnership organized under the laws of State A, conducted business in State B but failed to register as a foreign limited partnership as required by State B law.  On August 2, 2008, Robert Knight was tortiously injured in Chocolate County, State B, by a negligent act of ABC Partners.  At the time of the accident, Knight was a bystander observing acid being injected into an abandoned oil well by ABC Partners.  The injury occurred when a polyvinyl chloride (PVC) valve failed, causing a hose to rupture from its fitting and spray nitric acid on Knight, severely injuring him.  Knight sued ABC Partners and its limited partners to recover damages.  Are the limited partners liable?