如图,港口A在观测站O的正东方向,OA=4km,某船从港口A出发,沿北偏东15°方向航行一段距离后到达B处,此时从观测站O处测得该船位于北偏东60°的方向,则该船航行的距离(即AB的长)为____
Hello! This is my father. He is a writer.
Did you go to the hospital ____ (get) an X-ray?
若|m+2|+(n﹣1)2=0,则m+2n的值为( )