在做“探究小车速度随时间变化的规律”的实验中，电磁打点计时器应该接在50Hz的（填“高压”或“低压”______ 电源上．如图8所示是某次实验中得到的一条纸带，从比较清晰的点起，每隔4个打印点取一个点作为计数点，分别标明0，1，2，3，4，则相邻两个计数点之间的时间间隔为______s．现测得图中0与1两计数点间的距离s₁=30mm，3与4间距离s₄=48mm，则小车的加速度为______m/s²；小车在打点计时器打“3”这一点时的瞬时速度为______m/s．

—Perhaps, what I steal (偷) on the Happy Farm is not vegetables. That is "loneliness".

—________ This year"loneliness" is very popular. [ ]

A. I don't think so.

B. I quite agree with you.

C. That's a good idea.

D. I'm not sure if you are right.