あの少年は走っています。

that (someone or something distant from both speaker and listener, or situation unfamiliar to both speaker and listener)

boy; juvenile; young boy; youth; lad

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

to run; to travel (movement of vehicles); to drive; to hurry to; to retreat (from battle); to take flight; to run away from home; to elope; to tend heavily toward