66. We have to get the job done ____________(秘密地). We don't want others to know about it.

67. My train was 20 minutes late in the morning and there was a ___________(相似的)delay in the evening. 

68.Miss Li speaks English with excellent _______________(语音). 

69. This company is one of the Post Office's biggest _____________(顾客.客户).

70. The drowning swimmer required the lifeguard's _______________(即刻的)attention.

71. Our victory was ________________(庆祝) with music and dancing.

72. I've never seen a Shakespeare's play ______________(表演) so wonderfully.

73. Nowadays most people use paper _________________(手帕) .

74. The boy spoke in a very low voice , ___________(承认) he had broken the glass.

75.The_______________(大多数)of people in my neighborhood are Italian.

在做《研究匀变速直线运动》的实验时，某同学得到一条用打点计时器打下的纸带如图所示，并在其上取了A、B、C、D、E、F、G等7个计数点，每相邻两个计数点之间还有4个点图中没有画出，打点计时器接周期为T =0.02s的交流电源。经过测量得：d₁=3.60cm，d₂=7.70cm，d₃=12.32cm， d₄=17.41cm， d₅=23.00cm，  d₆=29.10cm。(以下结果均保留两位有效数字)

（1）通过计算，打出F点时物体的速度为v_F =_____________m/s；

（2）物体的加速度a =__________m/s²；

（3）如果当时电网中交变电流的频率是f =51Hz，而做实验的同学并不知道，那么加速度的测量值与实际值相比___________（选填：偏大、偏小或不变）