下列运算正确的是[ ]
A.a2·a3=a6
B.（a2）3=a5
C.2a+3a=5a
D.a3-a=a2
答案：C
在一定温度下，将1 mol CO和1 mol H2O(g)充入一密闭容器中发生反应：
CO(g)＋H2O(g)CO2(g)＋H2(g)，反应达到平衡后，测得CO2的物质的量为0.6 mol。然后再充入4 mol H2O(g)，达到新的平衡后，CO2的物质的量为[ ]
A．0.6 mol
B．1 mol
C．大于0.6 mol，小于1 mol
D．大于1 mol
Which of the following statements about a central bank's actions would most likely cause an immediate increase of the banking system's excess reserves（）
A. Decreasing the policy rate.
B. Selling securities in the open market.
C. Decreasing the required reserve ratio.
CO2(g)＋H2(g)，反应达到平衡后，测得CO2的物质的量为0.6 mol。然后再充入4 mol H2O(g)，达到新的平衡后，CO2的物质的量为[ ]