【假设】过氧化氢生成氧气的快慢与催化剂种类有关.
【实验方案】常温下,在两瓶相同体积的过氧化氢溶液中分别加入相同质量二氧化锰和氧化铁,测量各生成一瓶(相同体积)氧气所需要的时间.
图是小明在探究甲、乙、丙三种物质的质量与体积关系时作出的图像.分析图像可知
将下面的短文抄写在三线格中,注意大小写及标点符号。
his name is Tony smith. He's from cambridge. In his class, Tony and Lingling are thirteen years old and daming is twelve years old. they are good friends.