题目

Global English Club @ English training in four skills: listening, speaking, reading, and writing. @ 4-month (800 yuan), 6-month (1,400 yuan) and one year (2,500 yuan) courses. @ Choice of morning or evening classes, 3 hours per day, Mon.--Fri. @ All native teachers from Canada and USA. @ Tel: 8872806    Add: 306 Xinhua RoadBody-building Club @ All facilities(设备) supplied. @ On the top floor or Sunny Hotel. @ Every evening from 6:00 to 9:00, Mon.--Sun. @ Drinks and fruits ready for you during breaks. @ Tel: 6353188 @ Add: 369 Dunhuang RoadPiano Club @ One-to-one training on Sat. & 在“利用单摆测重力加速度”的实验中 (1)以下做法正确的是(　　) A．测量摆长的方法：用刻度尺量出从悬点到摆球间细线的长 B．测量周期时，从小球到达最大位移处开始计时，测出摆球完成一次全振动的时间 C．要保证单摆始终在同一竖直面内摆动 D．为了便于计时观察，单摆的摆角应尽量大些 (2)下表是一同学在实验中测得的数据： 组次 1 2 3 4 5 6 摆长l/m 0.500 0.600 0.700 0.800 1.000 1.200 周期平方T2/s2 2.10 2.80 2.70 3.20 4.00 4.60 ①上述数据中第________组肯定有错误，根据这些数据，在坐标图中作出l－T2图象； ②                                                                                                                     利用图象，求出当地重力加速度值g为________m/s2。(保留三位有效数字)