Liu Yu, a fifteen-year-old boy from Shandong, is a running star.

刘宇，一个来自山东的十五岁男孩，是一名跑步明星。

Police in American have stepped up their search for a fifteen-year-old boy who went missing three day ago in Dover , New Hampshire .

美国警方现已加快对一名五岁男孩的搜寻，该男孩于两天前在新罕布什尔州的多佛市失踪。