It _______ long before we ______ the result of the experiment.

A．will not be; will know

B．is; will know

C．will not be; know

D．is; know

在相同条件下，总质量为2g的CO和H₂的混合气体，在O₂中完全燃烧后全部通过足量的Na₂O₂固体，则固体质量增加[ ]

A．2g

B．1g

C．18 g

D．无法计算