Changing the design of a new product may ______ the risk of its production in the market.

A．bring about

B．come about

C．bring up

D．come up

在酸性条件下，KMnO₄与S^2-反应，正确的离子方程式是（）。

A、MnO₄-+S^2-+4H+=MnO₂+S↓+2H₂O

B、2MnO₄-+5S^2-+16H+=2MN₂++5S↓+8H₂O

C、MnO₄-+S^2-+4H+=MN₂++SO₂↑+2H₂O

D、2MnO₄-+S^2-+4H+=2MnO₄-+SO₂↑+2H₂O