elnd是什么牌子(
plelgraund是什么意思 -
美[ˈpleɪˌɡraʊnd]英['pleɪ.ɡraʊnd]n.操场；游乐场；运动场；娱乐场地游戏场；游乐园；儿童游乐场复数：playgrounds 例句筛选1.The children shout loudly on playground every afternoon.每天下午孩子们在操场上大声喧闹。2.We're still trying to d后面会介绍。
所以u=Skdi/dt 令L=Sk得u=Ldi/dt
美[ˈpleɪˌɡraʊnd]英['pleɪ.ɡraʊnd]n.操场；游乐场；运动场；娱乐场地游戏场；游乐园；儿童游乐场复数：playgrounds 例句筛选1.The children shout loudly on playground every afternoon.每天下午孩子们在操场上大声喧闹。2.We're still trying to d后面会介绍。
所以u=Skdi/dt 令L=Sk得u=Ldi/dt
