将24克氢气和氧气的混合气体点燃充分反应后，则生成水18克，混合气体中氢气可能为 [ ]

A．2克

B．4克

C．6克

D．8克

Speaker A: I’d like to buy a copy of Professor Franklin’s book on shells.
Speaker B: （）。

A. Are you one of Professor Franklin’s students

B. But I like his book on fish better than that on shells.

C. I’m sorry, sir. That book has been out of print for some time now.

D. Will you pay over there at the cashier