投资者的无差异曲线是由左至右向下弯曲的曲线，无差异曲线向下弯曲的程度大小反映投资者承受风险能力的强弱。( )

The C0₂ flooding system is actuated by a sequence of steps which are（）.

A.break glass，pull valve，break glass，pull cylinder control

B.sound evacuation alarm，pull handle

C.open bypass valve，break glass，pull handle

D.open stop valve，open control valve，trip alarm