图(甲)为一列横波在t=0时波的图象，图(乙)为该波中x="4" m处质点P的振动图象．下列说法正确的是    (    )

A．波速为5 m／s

B．波速为6 m／s

C．波沿x轴正方向传播

D．波沿x轴负方向传播

Not until the stadium of Bird’s nest was completed in the end _______ back to their normal position.

A．did our hearts got

B．did our hearts get

C．our hearts got

D．our hearts did get