题目

Read the following passage. Summarize the main idea and themain point(s) of the passage in no more than 60 words. Use your own words asfar as possible.HoldingParents Responsible—An Unfair Punishment The rise in teen crime suggests that some parents arefailing at their parental tasks. To correct the problem, lawmakers in somestates require parents to serve jail time. They hope that this punishment willmotivate parents to take their responsibilities seriously. Despite public support for parental responsibility laws,many people think that the laws are unfair. They suggest that parents shouldnot（1）探究小车加速度与合力、质量关系的实验装置如图甲所示：①若要探究小车的加速度与合力的关系，应保持______不变，分别改变施加在小车上的拉力F，测出相对应的加速度a．②把带有滑轮的长木板右端垫高，在没有牵引的情况下让小车拖着纸带以一定的初速度沿木板运动，打点计时器在纸带上打出一系列计时点，如果计时点间距______，就说明摩擦力和小车重力沿木板向下的分力平衡．③实验过程中，下列做法正确的是______A．先接通电源，再使纸带运动        B．先使纸带运动，再接通电源C．将接好纸带的小车停在靠近滑轮处  D．将接好纸带的小车停在靠近打点计时器处④实验中使用50Hz交变电流作电源，在打出的纸带上选择5个计数点A、B、C、D、E，相邻两个计数点之间还有4个点没有画出，测量了C点到A点、E点到C点的距离如图乙所示．则C点的速度vC=______m/s，纸带的加速度a=______m/s2．（结果保留三位有效数字）