下列各句中，没有语病的一句是（）

单句改错

①Struggled in a world of silence and darkness, Helen Keller seemed to be simple-minded.____

②The three Bronte sisters adopted this practice, Mary Ann Evans did the same.

____

③We decided to fight against this unfair system which prohibits us blacks sitting where we like.____

④Our friendship had developed quickly over the weeks that followed.____

⑤Maybe if I studied science then,I would have been able to give you more help.

____

小雷按图甲所示的电路进行实验，当闭合开关用电器正常工作时，电压表V₁和V₂的指针位置完全一样，如图乙所示，则L₁两端的电压为____ V，L₂两端的电压为____ V。