He ____ you more help even though he was very busy .

A．might have given

B．might give

C．may have given

D．may give

物质发生变化，下列叙述正确的是（　　）

A．生石灰堆放久了变质与水蒸气有关

B．氢氧化钠固体潮解变质与水蒸气、二氧化碳无关

C．钢铁生锈与二氧化碳、氧气、水蒸气有关

D．铜器表面生成铜绿与氧气、二氧化碳、水蒸气有关