更换或补焊后的叶轮未经找静平衡，禁止做（）。

下图示意某区域某月一条海平面等压线，图中N 地气压高于P地。读图，完成1—3题。

1、N地风向为 [ ]

A、东北风

B、东南风

C、西北风

D、西南风

2、M、N、P、Q四地中，阴雨天气最有可能出现在[ ]

A、M地

B、N地

C、P地

D、Q地

3、当M地月平均气压为全年最高的月份，可能出现的地理现象是[ ]

A、巴西高原处于干季

B、尼罗河进入丰水期

C、美国大平原麦收正忙

D、我国东北地区寒冷干燥

Now, we know that if we do not get enough vitamins, we are at risk of developing a number of diseases. As a result, vitamin supplements（补品），though expensive, are popular with people who worry that they are not getting enough vitamins from the foods they eat. But contrary to what many people think, medical experts have found little evidence that most supplements do anything to improve health or protect against disease.

In fact, medical experts warn that taking too many of some vitamins can be harmful. For example, too much vitamin E can cause bleeding. People should discuss what vitamins they take with their doctors, as some vitamins can produce harmful side effects when mixed with medicines.

Experts, however, do say that sometimes vitamins can help prevent disease. People who know they lack a particular vitamin should take vitamin supplements. Some older adults, for example, may not have enough vitamin B-twelve. This is because, as people get older, their body loses its ability to take it from foods. Also, people who spend much time inside may need some extra vitamin D as the skin makes this vitamin from sunlight.

Different vitamins are found in different foods. Vitamin A is found in fish liver oil. It also is in the yellow part of eggs. Sweet potatoes, carrots and other darkly colored fruits and vegetables contain substances that the body can change into vitamin A. Vitamin B-twelve is found in green leafy vegetables and other foods, like fruits. Vitamin K can be found in pork products.

In fact, for most people, a balanced diet can ensure enough of the vitamins our bodies need. So, it is important for us to eat a mixture of foods every day to ensure that we get enough vitamins our bodies need.

小题1:Vitamin supplements are popular with people because ________. 

A．people mistakenly think that they are good for their health

B．they contain more vitamins than the foods people eat

C．food does not provide enough vitamins people need

D．people fear that a lack of vitamins will lead to disease小题2:From the passage, we can learn that medical experts advise people _________.

A．never to take any vitamin supplements

B．to depend only on food for their vitamins

C．not to take any vitamins together with medicines

D．to consult doctors before taking vitamin supplements小题3:For people who lack Vitamin B-twelve, they can eat more from _______.

A. sweet potatoes   B. pork products   C. green leafy vegetables  D. eggs

42. What would be the best title of the passage?

A. Getting enough vitamins through a balanced diet.

B. Vitamin supplements do harm to our health.

C. Vitamins are important to our health.

D. Lacking vitamins can cause many diseases.

试述纵隔的定义、境界及其分区。

按规定建立完善井下安全避险设施；每年由总工程师组织开展安全避险系统有效性评估。

药瓶需贴有明显标签，剧毒麻醉药使用（）边标签。

A.红色

B.黑色

C.白色

D.蓝色