The price to book value ratio (P/BV) is a helpful valuation technique when examining firms:

A. with the same stock prices.
B. with different production methods.
C. that hold primarily liquid assets.

被定为与油气生产有关的最有毒的气体是（）

A、一氧化碳

B、甲烷

C、硫化氢

D、二氧化硫