There ______ some flowers on the teacher’s desk just now, but now there _____nothing on it. A. have; has B.were; was C. were; is D.has; has 答案:C17.关于运动,下列说法中正确的是( )A.匀变速直线运动是位移随时间均匀增大的运动B.匀变速直线运动是加速度随时间均匀变化的运动C.匀变速直线运动是瞬时速度随时间均匀变化的运动D.匀减速直线运动是位移随时间均匀减小的运动