【提出问题】：什么物质是该反应催化剂？

【查阅资料】铁与氧气、水反应生成铁锈，铁锈的主要成分为氧化铁．

选择最佳答语。

① Good morning. ____     A. Yes, I like sweets.

② What do you see? ____     B. I hear a sheep.

③ Do you like sweets?____     C. It's sunny.

④ What do you hear?  ____     D. Good morning.

⑤ How's the weather?____     E. I see a bee.

回族和维吾尔族等少数民族大多信仰（　　）