It is usually considered that living with disability is ().

A．challenged and frustrated

B．challenged and frustrating

C．challenging and frustrated

D．challenging and frustrating

使用环境腐蚀性强，要求钢材具有极洁净的表面以延长涂层的使用寿命，应采用（）除锈等级。

A、Sa1级

B、Sa2级

C、Sa2^1/2级

D、Sa3级