The students all well ____ (prepare) for the coming exams, so they all believe that they can easily pass them.
①海马②河蟹③沼虾④海豚⑤企鹅⑥水蛭
小红同学在做“探究平面镜成像”的实验时,将一块玻璃板竖直架在水平直尺上,再取两段完全相同的蜡烛A和B,点燃玻璃板前的蜡烛A,小心地移动蜡烛B,直到与蜡烛A的像重合,如图所示.在此实验中: