并购战略

⊙O₁与⊙O₂的半径分别是方程x²-7x+12=0的两根，如果两圆外切，那么圆心距d的值是______．

关于孟子“民贵君轻”的思想和明清之际对君主专制的批判思想的评述，正确的是 [ ]

A．都是从本质上否定君主专制

B．维护的阶级利益相同

C．产生的历史条件相同

D．都具有一定的进步性

阅读理解。

     Early people had very little effect on the environment. They lived in eaves in very small ' clan' groups.

They collected or killed only enough for the clan's survival. Early clans were nomadic, which means that

they did not stay in one place. Instead, they moved around, following the animals that were their main

food source and seeking areas where seasonal plants grew wild. Moving around seasonally helped to

protect the environment. The land had time to recover and animals had time to breed (繁殖) before the clan

returned for the next season.

     As time went by, these small family clans joined with others to form larger groups for protection. Joining

with other clans gave them more hunters and more women to help cut up the meat and share it between

families. Eventually, people tamed (驯养) wild animals such as dogs and horses. People settled around rivers

and fertile plains to share responsibilities and duties. Then, people began to plant crops instead of moving to

areas where the plants grew. This development changed the environment.

     Traditional forms of work also changed. Some people were hatter at performing a particular task than

other clan members, so they began to specialize in things they were good at doing. This also meant that they

began to exchange their goods for things that others produced.

     People began to communicate with distant tribes. Land was cleared for roads. Foreign plants and animals

were transported to places where they had not existed before. Specialization also gave people more free time.

So art, dance and music became important ways of expressing feelings and thoughts. This was how many

great civilizations started.

     Compared to the past, modern civilization has experienced many changes to become the highly developed

society that exists today. Populations have increased rapidly. Forests have been cleared for farms. Inventions

and technology have made work easier.

     However, pollution and other serious problems have also resulted from human progress. As concerned

citizens, it is up to us to learn from past mistakes and to help maintain and improve our environment.

1. Early tribes didn't have much effect on animal population because _____.

A. they kept animals for themselves

B. they ate only vegetables

C. they killed only enough for food

D. they loved animals

2. The main purpose for small clans to join together was _____.

A. to hunt animals

B. to seek safety

C. to share caves

D. to protect environment

3. Which of the following is TRUE according to this passage?

A. Early people moved to new places looking for new sources of food.

B. Modem civilization began when people started to live together in big groups.

C. Modem advancements are always good for the environment.

D. People began to exchange goods because they didn't have enough money.

4. It can be concluded from the passage that _____.

A. human progress has brought civilization to the society

B. civilization has improved traditional forms of work

C. our environment has been affected by human progress

D. early people understood environmental protection

管库员不得处理ABIS现金账务，不得兼任（）和调拨岗。库房管理必须坚持“账款分离”的原则。

A.记账岗

B.交换岗

C.复核岗

人类对传染病的斗争是从天花开始的。接种牛痘最终导致完全根除天花，并且推广为对抗许多病原体的可靠的保护方法。请在（）中填编号，横线上填文字。

图乙中当毒性强的Ｓ病原体进入接种过该疫苗的人体A，会发生二次免疫反应，此时图甲中的（）（）能分裂产生新的（），由（）（）细胞产生大量的⑤。