题目

California has lost half its big trees since the 1930s, according to a study to be published Tuesday and climate change seems to be a major factor(因素).The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.Many（2013?葫芦岛二模）工业上以大理石和赤铁矿为主要原料制取B和G．已知AG均有常见的化学物质，其中D、G为单质，各物质间有下图所示的转化关系．回答下列问题：（1）B物质是CaOCaO，反应①的用途工业制生石灰工业制生石灰；（2）写出反应②的化学方程式CO2+C 高温 . 2COCO2+C 高温 . 2CO，其反应类型是化合反应化合反应．（3）写出反应③的化学方程式3CO+Fe2O3  高温 . 2Fe+3CO23CO+Fe2O3  高温 . 2Fe+3CO2．