—Where is my pencil box?
—It's ____(on/ in) your desk.
①AD=BE=5cm;②当0<t≤5时,y= 25 t2;③直线NH的解析式为y=﹣ 25 t+27;④若△ABE与△QBP相似,则t= 294 秒,
其中正确结论的个数为( )