A computer cannot remember who_____; it simply does what _________.

A．will use it; it is told

B．uses it; it has told

C．used it; it is told

D．has used it; it told

总排风道内的瓦斯浓度不允许超过（）

A、0.75%

B、1.0%

C、1.5%

D、0.88%