三种水循环在各自的运动过程中都具备的环节是 A．蒸发和降水 B．蒸发、降水和径流 C．蒸发、降水、径流和水汽输送
Michael America on a cold spring morning. A. leave B. leaves C. left
摆长为l的单摆做小角度摆动，若摆球的质量为m，最大偏角为θ(θ<10°),则： （1）摆球经过最低点时的速度是多大？ （2）从最大位移处摆向平衡位置
函数f(x)＝的定义域为( ) A． (－∞，4] B． (－∞，3)∪(3,4] C． [－2,2] D． (－1,2]
This kind of car was _________ in 1890. A. discovered B. invented C. looked out D. found out
1. He is a man of _______ ideas and he often makes a careful plan _________. A. advanced; before advance B. advancing; in advance C. advanced; in advance D. advan
