问题
选择题
. -- Jack _______ for work in the downtown. What was the matter?
-- _______, but he had no luck.
A．ought to have hunted; So he was
B．ought to have hunted; So he did
C．ought to hunt; So he has
D．ought to hunt; So he did
答案
答案：B
3C(g)，若反应开始时充入2 mol A和2 mol B，达平衡后A的体积分数为a%。其他条件不变时，若按下列四种配比作为起始物质，平衡后A的体积分数大于a%的是( )