下列有关“电”的说法正确的是( )
A:摩擦起电的实质是创造了电荷
B:同种电荷相互吸引,异种电荷相互排斥
C:运动的电荷一定形成电流
D:电阻中有电流,它的两端一定有电压
In Sweden, people don't need to _______ too much money on presents, instead, making a meal is enough.
To his parents' d____ (高兴), he has made a full recovery after the accident.
有资料表明,被称为“地球之肺”的森林正以每年15000000公顷的速度从地球上消失,15000000这个数用科学记数法表示应是( )