阅读理解。

      Once there were three old men. They were rather forgetful. They always forgot what they

were doing.

      One of them said, "I always wonder if I want to buy a coat or a pair of socks." 

      The second old man said, "I often forget if I should put something in or take something out

of the fridge as soon as I open its door."

       "I am even more forgetful than both of you." Said the last old man,and he knocked at the table.

Then he turned to the other two men and asked,"Who just knocked at the table?"

1. The second old man said _____.

A. he forgot where he should go

B. he forgot whether he wanted to put something in the fridge

C. he forgot his key

2. The first old man forgot _____.

A. what he wanted to buy

B. where he wanted to go

C. what he should bring

3. The third old man said _____.

A. he was less forgetful than the others

B. he was more forgetful

C. he was remembering what he was doing

4. Who is the most forgetful?

A. The first old man

B. The second old man

C. The third old man

5. From the story we can know _____.

A. None of them are young

B. None of them is forgetful

C. The second old man is most forgetful

在20L恒容的密闭容器中，加入3molSO₃（g）和1mol氧气，在某温度下使其反应，反应至4min时，氧气的浓度为0.06mol/L，当反应到8min时，反应到达平衡．

（1）0min-4min内生成O₂的平均速率v（O₂）=______mol/（L•min）

（2）整个过程中，各物质的浓度与时间关系如图所示，则该温度下的平衡常数

K=______

（3）若起始时按下表数据投料，相同温度下达到平衡时，三氧化硫浓度大于0.05mol/L的是______，此时的平衡常数与（2）小题比较______（填“大于”、“小于”或“等于”）

①体系内压强不再改变

②容器内气体的密度不再改变

③混合气体的平均分子量不再改变

④V_正（SO₃）=2V_逆（O₂）

⑤n（SO₃）：n（O₂）：n（SO₂）=2：1：2．