On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3 ？（）

A．5

B．50

C．10⁵

D．5¹⁰

E．8¹⁰-3¹⁰

飞行中如果需要使用氧气，则应注意的问题之一是（）。

A.严格避免以油脂为基本原料物品与纯氧接触

B.用氧过程中禁止用明火点烟，但可用点烟器

C.用氧过程中禁止使用明火，氧结束后可使用明火