下列关于人类染色体的叙述中，错误的是 [ ] A．形成生殖细胞时，成对的染色体要

阅读理解。

      Most people around the world are right-handed. This also seems to be true in history. In 1997, scientists

studied works (作品) of art made at different times from 15,000 B.C. to the 1950s. Most of the people shown in

these works are right-handed, so the scientists guessed that right-handedness has always been common through

history. Today, only about 10% to 15% of the world's population is left-handed.

      Why are there more right-handed people than left-handed ones? Scientists now know that a person's two

hands each have their own jobs. For most people, the left hand is used to find things or hold things. The right

hand is used to work with things. This is because of the different work of the two sides of the brain (大脑).

The right side of the brain, which makes a person's hands and eyes work together, controls the left hand. The

leftside of the brain, which controls the right hand, is the centre for thinking and doing problems. These findings

show that more artists should be left-handed, and studies have found that left-handedness is twice as common

among artists than among people in other jobs.

      No one really knows what makes a person become right-handed instead of left-handed. Scientists have

found that almost 40% of the people become left-handed because their main brain is damaged (损害) when they

are born. However, this doesn't happen to everyone, so scientists guess there must be another reason (原因),

why people become left-handed. One idea is that people usually get right-handed from their parents. If a person

does not receive the gene (基因) for right-handedness, he/she may become either right or left-handed according

to the chance (偶然性) and the people they work or live with.

      Though right-handedness is more common than lefthandedness, people no longer think left-handed people

are strange or unusual. A long time ago, left-handed children were made to use their right hands like other

children, but today they don't have to.

1. After studying works of art made at different times in history, the scientists found ________. [ ]

A. the art began from 1 500 B.C.

B. the words of art ended in the 1950s

C. most people shown in the works of art are right-handed

D. most people shown in the works of art are left-handed

2. How many people in the world are left-handed now? [ ]

A. Less than one sixth.

B. More than a half.

C. About 40 %.

D. The passage doesn't tell us.

3. What is the left hand for most people used to do?[ ]

A. It's used to find or hold things.

B. It's used to work with things.

C. It's used to make a person's eyes work together.

D. It's the centre for thinking and doing problems.

4. According to (根据) the passage, which of the following is NOT true? [ ]

A. No one really knows what makes a person become right-handed.

B. Left-handedness is cleverer than right-handedness.

C. Today children are not made to use their right hands only.

D. Scientists think there must be some reason why people become left-handed.

5. The best title (题目) foe this passage is ________. [ ]

A. Scientists' New Inventions

B. Left-handed People

C. Which Hand

D. Different Brain, Different Hands

硝酸铵（NH₄NO₃）是一种常见的氮肥．请通过计算回答：

（1）硝酸铵的相对分子质量为______．

（2）硝酸铵中氮元素、氢元素、氧元素的质量比为______．

（3）某花卉基地需要配置100kg10%的硝酸铵溶液，基地的实验室中现有200kg5%的硝酸铵溶液和50kg30%的硝酸铵溶液，若选用这两种溶液混合配制，应该如何进行？

阅读下面的古诗，然后回答问题。（7分）

灞上秋居

马戴

灞原风雨定， 晚见雁行频。

落叶他乡树， 寒灯独夜人。

空园白露滴， 孤壁野僧邻。

寄卧郊扉久， 何年致此身？

小题1:颔联和尾联在抒情方式上有什么不同？（3分 ）

小题2:“空园白露滴， 孤壁野僧邻”渲染了什么氛围？写法上有什么特点？（4分）

表中两种所有制经济百分比出现的主要原因是：

A．土地改革的基本完成

B．三大改造的基本完成

C．家庭联产承包责任制的实行

D．国有企业改革的深化

装配时对刚度较低的构件，应考虑加装支撑件或支撑工具。( )