—______is your birthday gift, Linda?
— It's a circle.
A:What kind
B:What color
C:What time
D:What shape
如图所示,当开关S闭合,甲乙两表为电压表时,两表的读数之比U甲:U乙为4﹕1,当开关S断开,甲乙两表为电流表时,两表的读数之比I甲:I乙为( )
— ______________?
— I can't find my English book.