—______. We don't have enough money.
A:Sounds great
B:I am afraid not
C:Don't mention it.
如图表示某一高度上的气压分布状况,A、B为等压线,PA>PB,读图回答下题.
如图为某生态系统中的食物网示意图。若E生物种群含有总能量5.8×109 kJ,B生物种群含有总能量1.3× 108 kJ,则从理论上讲,A生物种群含有的总能量至少是