[单选题]

£«2.00DC×90°与£2.00DC×180°联合后得到( )
A．+2.00DS／-2.00DC×90°
B．+2.00DS／-4.00DC×180°
C．+2.00DS／-4.00DC×90°
D．-2.00DS／+2.00DC×90°
E．-2.00DS／+4.00DC×180°

£«2.00DC×90°与£­2.00DC×180°联合后得到( )A．+2.00DS／-2.00DC×90°B．+2.00DS／-4.00DC×180°C．+2.00DS／-4.00DC×90°D．-2.00DS／+2.00DC×90°E．-2.00DS／+4.00DC×180°