特别用途线是指安全线和（）。A.避难线 B.岔线 C.到发线

(三)某商品流通企业想和供应商建立一种长期合作的关系，该企业有甲乙丙丁四家供应商，现该企业决定首先对这四个供应商的供货情况进行评审。根据四个供应商的供货情况确定了6项评分指标，每项指标分为5个档次：好、较好、一般、较差、极差。每个档次的分值分别为：好，5分；较好，4分；一般，3分；较差，2分；极差，1分。四个供应商的得分情况如下表所示。

根据表中数据，若采用评分法选择，较理想的供应商是（）。

A．甲

B．乙

C．丙

D．丁

阅读理解。

     Scientists have found what look like caves on Mars (火星), and say they could be protecting life from

the planet's terrible environment.

     The first caves discovered beyond the Earth appear as seven anysterious black dots on the pictures sent

back by NASA's Mars Odyssey orbiter. Each as large as a football field, they may be openings into natural

caves below the Martian suface.

     "If there is life on Mars, there is a good chance you'd find it in caves," said Jut Wynne, one of the

researchers who noticed the features while working on a US Geological Survey Mars Cave Detection

Program.

     Jonathan Clarke, a geologist with the Mars Society of Australia, yesterday described the discovery as

exciting.

     One photo taken at night by an infrared imager (红外线成像器) showed one hole to be unusualy warm,

suggesting hot air trapped during the day is flowing out.

      "I said:'Wow, that's a cave'" Dr. Clarke said excitedly." People have been looking for these for a long

time; now we have found them."

      He agreed such caves would be perfect places to hunt for life escaping from the bitterly cold,

radiation-soaked (充满辐射的), dry surface.

     "Tiny drops of water could collect inside," he said. "If there are gases coming out, they could provide

energy for a whole range of bacteria. A cave is also a protection from radiation; the surface of Mars is

exposed to high levels of space radiation."

     The caves probably formed when tube-shaped lave flows (管状岩浆流) spread across the planet long

ago. The outside of the tubes cooled, forming solid walls, while something hotter inside allowed the

remaining have to flow out, forming caves.

1. What does the passage mainly talk about?

A. How the caves were formed on Mars.

B. How scientists found these caves on Mars.

C. Caves on Mars may be full of hot air or a sign of life.

D. Scientist have completely recognized the surface of Mars.

2. We can learn from the passage that _____.

A. water has already been found on Mars

B. the scientists found all the caves at night

C. it is certain that there is life in these caves

D. the surface of Mars is bitterly cold, radiation-soaked and dry

3. According to the passage, Dr. Clarke was so excited because _____.

A. such caves could provide energy for life

B. they had finally found the caves on Mars

C. such caves would be perfect places to hunt for life

D. scientists had long been looking for these caves

4. Necessary conditions for life on Mars mentioned in the passage may include _____.

A. lava and energy

B. water and radiation from space

C. gases and lava

D. water and protection from radiation

从需求方面讲，影响旅游需求的因素有（）

A.收入水平

B.余暇时间

C.旅游动机

D.身体能力状况

E.家庭负担

F.目的地的资源供给能力

线路电压为154～220 kV的导线与建筑物之间的最小垂直距离为( )。

A．6.0m

B．7.0m

C．8.0m

D．9.m

通常圆柱齿轮副的传动比小于等于（）

A、5

B、6

C、7

D、8