“Did you ask your boss for a pay increase?” she asked her husband.
(间接引语) She asked her husband ____ he had asked his boss for a pay increase.
如图所示的四幅图中能说明电磁继电器的工作原理的是( )
化简:a2-1a÷1+1a=____
烧开水时,壶盖被水蒸气顶起,这时水蒸气的 ____能转化为 ____能.