It was reported in the newspaper that one of our students got the first place in the last Provincial Chemistry Olympic Contest           in June．

A．having been held

B．to be held

C．being held

D．held

△ABC中，AB=63，BC=15，AC=49，和它相似的三角形的最短边是5，则最长边是[ ]

A．18

B．21

C．24

D．17