公安部门要求小型客车的驾驶员和前排乘客必须使用安全带 （或安全气囊），这主要是为了防止高速行驶的汽车在　____ 　时，乘车者由于　____ 　而撞伤，使用安全带（或安全气囊）可以起到保护安全的作用。

罗斯福“新政”的成功，为困境中的自由经济打开了通道。对经济生活不能袖手旁观，成为以后美国历届政府的基本信条。此“基本信条”是（    ）

如图是“探究电流通过导体时产生的热量与什么因素有关”的实验装置．将此装置接到电源两端，通过控制 ____相同，探究电流产生的热量与 ____的关系．在电路中再串联一个滑动变阻器、一个电流表，再接入原电路，还可以探究电流产生的热量与 ____的关系．

    Hello! I'm Linda. I have a good e-friend. Her name is Zhang Yun. Her English name is Betty. She is a Chinese girl, but she lives in the UK with her parents. Her father is a doctor and her mother is a teacher. She is ten years old. She call me big sister. She is good at English. She likes Chinese and I also like Chinese. She likes singing and playing basketball. This is my good e-friend. Do you want to know more?