Jurors heard closing arguments Thursday in the only trial to arise thus far from the Flint water crisis, a dispute over whether two engineering firms should be held partially responsible for the city’s lead contamination in 2014-15. Attorneys representing four Flint children said Veolia North America and Lockwood, Andrews & Newman, known as LAN, didn’t do enough to get the city to treat the highly corrosive water or to urge a return to a regional water supplier. Veolia and LAN, which performed work for Flint, were not part of a landmark $626 million settlement involving Flint residents, the state of Michigan and other parties.