如图变压器初级线圈是500匝,次级线圈是1000匝.初级接在电动势是6v的干电池两极,则此时次级得到的电压是( )
A.12v
B.3v
C.6v
D.0v
答案:D
practicing about 10 times, the students gave a concert.
A.While
B.When
C.Before
D.After
数学二进制数为逢十进一。