题目

Now that we have entered the cities and ________, we should work as servants of the people. A . came to use B . came to power C . came to life D . came to office 答案：B在2004年中考体育达标“跳绳项目”测试中，燕燕同学1min跳了120次，每次跳起的高度约为4cm，若她的质量为50kg，则她跳一次做的功约为    J，她跳绳的平均功率约为    W．（g取10N/kg）