+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°