题型:判断题 一物体做直线运动,前一半位移内的平均速度是3m/s,后一半位移内的平均速度是2m/s,则整个位移内的平均速度为( )A.2.5m/sB.1.2m/sC.2.4m/sD.2.3m/s 查看答案
题型:判断题 —How many birds can you see in the trees? —I can see ________birds in them. [ ]A. hundreds of B. five hundreds C. hundred of D. five hundreds of 查看答案