下列反应属于分解反应的是____

A、铁+氧气 $\stackrel{点燃}{\to }$ 四氧化三铁              B、水 $\stackrel{通电}{\to }$ 氢气+氧气

C、甲烷+氧气 $\stackrel{点燃}{\to }$ 水+二氧化碳       D、____．

泡菜是一种特色小吃，酸奶是有益的酸性乳品，这是利用何种微生物的发酵作用 （   ）

划分发达国家与发展中国家的依据是（　　）

______housing prices are going up madly, it is almost certain that the local government focuses not on improving people’s life but on trying to earn money by selling state land.

The conference has been held to discuss the effects of tourism _________ the wildlife in this area.