A new underground ________ Wuxi ________ Shanghai will be built soon. A. connected; and B. connects; with C. connected; to D. connecting; to 答案:D 20.某同学在做“用单摆测重力加速度”实验中,先测得摆线长为97.50cm,摆球直径2.00cm,然后用停表记录了单摆振动50次所用的时间如图所示,则(1)该摆摆长为98.50cm,停表表示读数为99.8s.(2)如果测得的g值偏小,可能的原因是BA.测摆线时摆线拉得过紧B.摆线上端悬点未固定,振动中出现松动,使摆线长度增加了C.开始计时时,停表过迟按下D.实验时误将49次全振动数为50次.