A group of Marines in their dress uniforms trudged through floodwaters near the Pentagon last Thursday to help a stranded motorist.  A torrential downpour had flooded a number of roads in the area, and the Marines pushed the car out.    In a video, a woman in the car says, “The Marines are going to help us?  . . . this is the most American thing ever.”  And in the comments, she added, “As an immigrant we don’t usually see these things in the country I grew up in.”