(2015•北海)下列哪种现象属于摩擦起电( )
①渔人甚异之____
②便要还家____
③无丝竹之乱耳____
④其两膝相比者____
⑤矜、寡、孤、独、废疾者皆有所养____
⑥虽乘奔御风____