文中描写秦王从“怫然怒”到“色挠”的脸色变化有何作用？（2分）

新物种形成的标志是[ ]

A．具有新的生理功能

B．出现新的形态结构

C．出现地理隔离

D．形成生殖隔离

The factory produced a great number of computers, most of _______ shipped to foreign countries.

A．them

B．which

C．it

D．what

根据句意，用所给单词的适当形式填空。

1. In one place I saw children ________ (work) for a cruel boss.

2. I have been to Hong Kong ________ (one).

3. There are some less ________ (develop) countries in Africa.

4. China's economy is ________ (increase) rapidly.

5. Have you spent the whole day ________ (consider) it?

急性根尖周脓肿时。医生建立最佳的引流通道是（）

A.根尖孔-根管-龋洞

B.根尖部-牙周袋

C.根尖部-齿槽骨-黏膜下

D.根尖部-齿槽-骨-皮肤下

E.根尖部-牙周间隙-龈袋

简述深井泵出水量偏低的原因有哪些？