A:The piano lesson
B:The guitar lesson.
C:The violin lesson
下列人体所需的营养物质与缺乏症对应错误的是( )
① 23 x - 12 x =10
② x :4 =0.25
③3∶2.5=2∶ x
例:193.5=4.5 × 43=45 × 4.3
①19.35=____ × ____=____ × ____
②1.935=____ × ____=____ × ____