列宁在《十月革命四周年》一文中说：“我们也学会了——至少是在一定程度土学会了革命所必需的另一种艺术：灵活机动，善于根据客观条件的变化而迅速急剧地改变自己的策略，如果原先的道路在当前这个时期证明不合适，走不通，就选择另一条道路来达到我们的目的。”文中“另一条道路”是指实行（    ）

如图所示，用长为L的轻绳把一个小铁球悬挂在高2L的O点处，小铁球以O为圆心在竖直平面内做圆周运动且恰能到达最高点B处，若运动中轻绳断开，则小铁球落到地面时的速度大小为（   ）

在△ABC中，角A、B、C对应的边分别是a、b、c，已知3cosBcosC+2=3sinBsinC+2cos²A．

（I）求角A的大小；

（Ⅱ）若△ABC的面积S=5$\sqrt{3}$，b=5，求sinBsinC的值．

—Hi, Mrs. Green How was your trip to the United States?

—It was wonderful____

—____

—I was there for a month.

—Great.____

—Yes, it's a wonderful and exciting city.

—____

—The city is the main business and cultural center in the Midwest It's famous for its music opera and theaters as well as for its excellent museums.

—____

—Yes, sure. What would you like to know?