首先使用钠石灰将二氧化碳吸收法用麻醉者是（）

A.Waters

B.Lavoisier

C.Rovenstine

D.Snow

E.Walter

People will find themselves suffering from headache and watering eyes, and even snowhlindness, when______to several hours of "snow light".

A．being exposed

B．having been exposed

C．exposed

D．exposing