给蓄电池充电的过程中，电能转化为蓄电池的_________能；用手机打电话时，是利用_________来传递信息的。
化学；电磁波
急、慢性血栓的主要区别是（）。
A.血栓形成
B.血栓再通血流信号可增多
C.血栓局部不能压瘪
D.血流信号消失或减少
E.血栓回声强弱和管腔有无扩张
Why will Bob and Sarah write a letter to the dean about the computer center
A. To ask for permission to use it at special hours.B. To get the broken computers removed.C. To complain about the technical assistant.D. To request additional computers and longer hours.
