对食品生产经营人员的卫生要求，错误的是（） A.新参加工作和临时参加工作的食品生产经

For thousands of years, people have used plants to make medicines. They used different parts of the plants —the roots, the leaves, the flowers, and the bark (树皮). Today, doctors have rediscovered more medicinal (药用) values of some plants. Let’s look at some examples.

Foxglove is a common plant. People have used it to make the heart slow down. Recently scientists have developed another drug from it. This new drug helps prevent other heart problems.

In some areas, malaria has been a problem. Scientists have learned that the bark of a South American tree, the cinchona, can be made into a drug to prevent malaria. For a long time, the Chinese have known that a special plant, wormwood, can also fight malaria. Scientists have been working with it to develop new drugs against malaria.

In Germany, some scientists studied garlic (大蒜) for four years. They found that it helps prevent the build-up of plaque (血小板) because too much plaque is bad for health. This very common plant continues to be studied.

As we know, there are about 250,000 kinds of flowering plants in the world. Scientists have only studied little more than one percent of plants for their medicinal value. Maybe medicines for AIDS and cancer will be made from the other 99 percent.

小题1:What can foxglove be used for?

A．Studying plants.

B．Building up the plaque.

C．Treating AIDS and cancer.

D．Preventing heart problems.小题2:What does the underlined word “malaria” in Paragraph 3 refer to (指的是)?

A．A drug.

B．A plant.

C．An illness.

D．An animal.小题3:How many plants are mentioned in the passage?

A．3.

B．4.

C．5.

D．6小题4:Which of the following is the best title for the passage?

A．Past and future

B．Plants and medicine

C．Health and illness

D．Scientists and doctors

蛋白质是日常生活中人类必须的六大营养素之一，向两支盛有蛋白质溶液的试管中分别加入一定量的饱和硫酸铵溶液和硫酸铜溶液时都会出现沉淀，这两个作用过程被分别称为      和      ，区别两种作用的简单方法是                         。

请用学过的化学知识，解释下列生活中的现象．（在下列（1）（2）两小题中任选一题回答，若两小题都回答，则以第（1）小题的答案评定分数．）

（1）用水壶烧开水一段时间后，水壶内常结有水垢．

（2）盛水的铁锅与水面接触的位置有明显的锈斑．

孕产妇死亡率的分母是（）。

A.女性人口数

B.年活产数

C.人口总数

D.育龄妇女数

E.年平均人口数

化学品是指各种化学元素、由元素组成的化合物及其混合物，包括天然的或人工的。