肺气肿病人应用吸入麻醉可表现为（）

A.加深快、苏醒快

B.加深慢、苏醒快

C.加深快、苏醒慢

D.加深苏醒均慢

E.加深苏醒均无变化

Why does the Earth show almost no signs of having been hit by numerous meteors in the past

A．Humans have built over most of the craters.

B．Most meteors fell into the ocean and not on land.

C．The Earth's magnetic field repelled most meteors.

D．The Earth's natural geologic activity has eliminated most traces.