政府组织购买社会工作服务，原则上应通过（）方式进行。 A.公开招标 B.邀请招标 C

植物缺氮会导致生长迟缓或停滞．以下化肥中属于氮肥的是（　　）

A．NH₄NO₃

B．K₂SO₄

C．KH₂PO₄

D．K₂CO₃

压力的“一般适应症候群”是指，不处于压力下的个体反应的阶段性是（）

A、警戒阶段

B、抗争阶段

C、应对阶段

D、枯竭阶段

Astronomers (天文学家) say they are on the point of finding planets like Earth orbiting other stars, which is a key step in determining if we are alone in the universe.

A top NASA official and other leading scientists say that within four or five years they should discover the first Earth-like planet where life could develop, or may have already. A planet close to the size of Earth could even be found sometime this year.

At the annual American Astronomical Society conference this week, each discovery involving  so-called “exoplanets” —those outside our solar system —pointed to the same conclusion：Quiet planets like Earth where life could develop probably are plentiful.

NASA’s Dew Kepler telescope and a lot of new research from the suddenly hot and competitive exoplanet field caused noticeable buzz at the meeting．Scientists are talking about being at “an incredible special place in history” and closer to answering the question. “Are we alone? For the first time, there’s an optimism that sometime in our lifetimes we’re going to get to the bottom of that,” said Simon Worden，an astronomer who heads NASA’s Ames Research Center. “If I were a betting man, which I am, I would bet we’re not alone.”

“These are big questions that reflect upon the meaning of the human race in the universe,” the director of the Vatican Observatory, the Rev. Jose Funes, said Wednesday in an interview at this week’s conference.

Worden told The Associated Press: “I would certainly expect in the next four or five years we’d have an Earth-sized planet in the habitable (可居住的) zone.”

What is very important in determining if we are alone in the universe?

A. Finding an Earth-like planet.       B. Orbiting other stars.

C. Developing new telescopes.      D. Finding more exoplanets.

What’s an exoplanet?

A. It’s a planet like Earth.        B. It’s a planet outside our solar system.

C. It’s a planet orbiting the sun.   D. It’s a planet where life have developed.

The underlined phrase “get to the bottom of” probably means “__________”.

A. understand fully    B. make full use of

C. search for         D. do more research on   

From the passage we can learn that __________.

A. an Earth-like planet has been found

B. it’s been proved we are not alone in the universe

C. Jose Funes has found the meaning of the human race in the universe

D. the discovery of an Earth-like planet could happen in the near future

医学指标血清淀粉酶(AMY)活性测定结果明显超过正常值提示病人可能患

A．肝癌

B．糖尿病

C．肝硬化

D．急性胰腺炎

E．缺铁性贫血

分离高沸点物质的混合物，通常采用的蒸馏方式是（）。

A.减压蒸馏

B.常压蒸馏

C.萃取蒸馏