A:石墨可用于制铅笔芯
B:稀有气体可用来制作电光源
C:水银可用来制温度计
D:氮气可用于食品包装中防腐
在如图所示的实验装置中,用棉线将铜棒ab悬挂于磁铁N、S极之间,铜棒的两端通过导线连接到灵敏电流计上.当铜棒向左运动时,电流计的指针 ____(选填“偏转”或“不偏转”).该装置可将 ____能转化为电能.写出用该原理制成的一种设备: ____
Food is very important to our health. Everyone needs to eat well if he or she wants to have a strong body.Our minds, like our bodies, always need the best food. This kind of food is knowledge. We start getting knowledge when we are very young.