某同学仿照“探究小车速度随时间变化的规律”这一实验，利用如图所示的装置测量重物做自由落体运动的加速度。

（1）对该实验装置及其操作的要求，下列说法正确的是： [ ]

A．电磁打点计时器应接6V交流电源

B．打点计时器的两个限位孔应在同一条竖直线上

C．重物最好选用密度较小的材料，如泡沫塑料

D．开始时应使重物靠近打点计时器处并保持静止

E．操作时，应先放开纸带后接通电源

F．为了减小误差，应重复多次实验，在打出的纸带中挑选一条最清晰的。

G．为了便于测量，一定要找到打点计时器打下的第一个点，并选取其以后各连续的点作为计数点。

（2）图是某同学在实验中得到的一条较为理想的纸带。把开头几个模糊不清的点去掉，以较清晰的某一个点作为计数点1，随后连续的几个点依次标记为点2、3、4。测量出各点间的距离已标在纸带上，己知打点计时器的打点周期为0.02s。打点计时器打出点2时重物的瞬时速度为_____________m/s，物体做自由落体运动的加速度的值约为________________m/s²。（本题计算结果保留3位有效数字）

Most taxpayers have had enough income tax collected by their employers during the year. So they do not (36) any money. In fact, most Americans get some money back. Last year, the Internal Revenue Service returned at least some money to more than (37) Americans paying individual income tax.
The United States has what is called (38) . Tax rates increase as (39) increase. This year, people earning more than (40) are taxed at the highest rate.
Earnings above that amount are taxed at (41) . Earnings below that amount are taxed at lower rates.
Individuals who earn less than (42) pay no income tax. But they do pay (43) , Medicare and other taxes.
There are many different ways for people and businesses to reduce their (44) Most homeowners, for example, can reduce their taxes a little by reporting to the I.R.S. the interest they pay (45) . This is called a (46)
In 2004, personal income taxes provided the government with most of its money: (47) of the budget. Social security and other (48) taxes provided (49) . Other forms of income include (50) , money borrowed to (51) and special taxes on (52) .
But income from taxes did not provide enough to pay for government spending. The I.R.S. says the budget deficit for 2004 was about (53) dollars.
Preparing tax documents can be complex. The I.R.S. estimates that taxpayers need an average of about 13 hours to prepare tax documents. And that is just for the basic tax form. For business, the I.R.S. estimates an (54) needs more than 50 hours. This is why a lot of Americans pay (55) to complete their tax documents for them.