下列哪型病毒感染是机体获得特异性免疫的主要来源( ) A．急性感染 B．慢性感染

1881年美国全国性的职业棒球组织——（）成立。

电空制动控制器在重联位时，（）。

A.中继阀自锁

B.均衡风缸不能与制动管沟通

C.重联电空阀不得电

D.总风遮断阀开放

阅读理解。

     Scientists in Mexico have just begun a new study of one of the world's biggest pyramids: the

Pyramid of the Sun, north of Mexico City. They're putting lots of small, high-tech machines under

the pyramid to try to unlock some of its secrets. For thousands of years, people have tried to uncover

the secrets of the pyramids.

     The people who built the pyramids made lots of secret doors and rooms to stop robbers from

finding the treasures inside. However, there always have been some smart thieves in history. Now,

almost all of Egypt's pyramids have been robbed, including the Great Pyramid of Khufu, which is

the largest pyramid in the world. It is the only one of the ancient wonders of the world that is still

standing.

     In AD 820, an Arab king named Abdullah AL Manum got a group of workers to dig their way

into the Great Pyramid and have a look. Inside the pyramid, they found three rooms-the Queen's

Chamber, the Grand Gallery and the King's Chamber. But to their surprise, the men didn't find the

treasures they wanted. The Queen's and King's Chambers were both empty! Where were the King's

mummy and his treasures? Had someone already taken them away? The huge stone doors at the

pyramid's entrance were still closed when AL Manum's men went inside. How had the thieves got

in and out?

     Since then, many people have gone inside the Great Pyramid to have a look or to try to take things.

But still, no other chambers or walkways have been found.

     In 2002, an American team made the most recent visit to the Great Pyramid. Scientists sent a robot

into the pyramid, but they only found a mysterious locked stone door.

1. The first two paragraphs were written to show that ____. 

A. the Pyramid of the Sun is an unusual historic building 

B. ancient Egyptian emperors were cruel 

C. construction workers led a hard life in ancient Egypt 

D. the secrets of the pyramids remain to be uncovered

2. What is the purpose of making some secret doors to the pyramids?  _______. 

A. To try to unlock some of its secrets 

B. To stop robbers from finding the treasures inside 

C. To refuse some visitors all over the world into it 

D. To tell the truth to the people in the future

3. Which of the following is NOT true to the Great Pyramid of Khufu? ______. 

A. It is the largest pyramid in the world.   

B. It is the only one of the ancient wonders that is still standing. 

C. Abdullah AL Manum took the King's mummy and his treasures away 

D. Scientists found a mysterious locked stone door to the Great Pyramid

4. What would be the best title for the text?

A. The Pyramid of the Sun      

B. The Great Pyramid of Khufu 

C. A Mysterious Locked Stone Door  

D. Unlocking the Doors of History

关于影响药物肾排泄相互作用的叙述不正确的是（）

A.可通过肾小管主动转运机制排泌入尿液的药物，同时应用时可存在排泌竞争

B.肾血流对一些药物的肾排泄有重要影响

C.非甾体抗炎药可通过抑制前列腺素减慢肾血流而影响一些药物的排泄

D.较易经肾排泄的药物不会影响相对较难经肾排泄药物的正常排泄

E.丙磺舒可影响青霉素类药物的排泄

当超导材料的温度低于临界温度而进入超导态以后，该超导材料便呈现完全抗磁性，这种现象称为“（）”。

A.超导效应；

B.迈斯纳效应；

C.光电效应；

D.量子效应。