Chinese President Xi Jinping appeared at the Sochi Olympic opening ceremony, ______ China’s strong support for the Olympics and Russia’s efforts to host the Games.

A．signing

B．symbolizing

C．sponsoring

D．signaling

电弧炼钢炉属于（）。

A.一类负荷；

B.二类负荷；

C.三类负荷；

D.其他负荷。