已建立化学平衡的某可逆反应，当改变条件使化学平衡向正反应方向移动时下列有关叙述正确的是 （ ）
①正反应速率一定大于逆反应速率 ②反应物的浓度一定降低 ③反应物的转化率一定增大 ④生成物的产量一定增加 ⑤生成物的体积分数一定增加．
A．①②③④⑤
B．①④
C．①②④
D．①②
①正反应速率大于逆反应速率，平衡向正反应方向移动，故①正确；
②如增大反应物的浓度，平衡向正方向移动，达到平衡时，反应物的浓度比改变条件前大，故②错误；
③如增加某反应物的物质的量，平衡向正方向移动，但该反应物的转化率反而减小，故③错误；
④化学平衡向正反应方向移动，生成物的产量一定增大，故④正确；
⑤如增加反应物的物质的量，平衡向正方向移动，若增加的多，转化的少，则生成物的体积分数反而减小，故⑤错误．
故选B．
Not all people like to work but everyone likes to play. All over the world men and women, boys and girls enjoy _____. Since the days of long ago, adults and children have called their friends together to spend_____, even days playing games. Sports help people to live______. They help to keep people healthy and feeling good. When they are playing games, people _______ a lot. This is good for their health. Having ______ with their friends makes them happy. Many people enjoy sports by watching others _______. In small towns, crowds meet to watch the bicycle races or the soccer games. In big cities, thousands _______ to see an ice-skating or a baseball game. What are your favorite sports? Is the weather _______where you live? Then swimming is probably one of your sports. Boys and girls in China love to _______. There are wonderful beaches and there are beautiful ______ and lakes across the country. The weather is also good for swimming.
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下表是某国出生率、死亡率的变化情况，下图是人口增长模式图。回答第题。
| 1975年 | 1985年 | 1995年 | 2005年 | |
| 出生率（%） | 4.4 | 4.3 | 4.3 | 4.3 |
| 死亡率（%） | 2.0 | 1.7 | 1.6 | 1.4 |
小题1:该国处于图中的（ ）
A．阶段I
B．阶段II
C．阶段III
D．阶段IV小题2:该国1975～2005年期间，人口增长的特点是（ ）
A．总量有波动，但变化不大
B．总量上升，增长速度加快
C．经历了慢—快—慢的过程
D．总量上升，增长速度减缓