在锅炉热备过程中，应主要监测炉水的（） A.加药量 B.pH值 C.溶氧 D.电导率

如图曲线a、b表示两类生物种群密度与存活率之间的关系。下列分析错误的是

A．曲线a代表的种群个体一般体型较大，营养级较高

B．依据曲线b，人工养蜂时种群密度中等最好

C．对大型动物迁地保护，迁移的种群密度不宜过大

D．种群密度为d时，曲线b代表的种群个体间竞争最剧烈

下图中甲、乙、丙反映了三类工厂的投入构成情况，据此回答1—3题。

1、下列工业部门中，与甲类工厂特征相符合的是[ ]

A、家具业

B、纺织业

C、制糖业

D、炼铝业

2、乙类工厂运费低的原因最不可能是[ ]

A、需要的能源少 　

B、产品科技含量高

C、需要的原料少 　

D、靠近原料地和消费市场

3、现阶段，丙类工厂适宜布局在我国[ ]

A、环渤海地区

B、长江三角洲地区

C、中、西部地区

D、珠江三角洲

下列选项中，不属于证券发行的原则的是( )。

A．诚信

B．公开

C．公平

D．公正

精馏操作的恒摩尔气化假设的内容是什么？

(四)

With only about 1 000 pandas left in the world, China is desperately trying to clone the animal and save the endangered species. That’s a move similar to what a Texas A ＆ M University researchers have been undertaking for the past five years in a project called "Noah’s Ark’.

Noah’s Ark is aimed at collecting eggs, embryos, semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species, should become extinct, Dr. Duane Kraemer, a professor in Texas A ＆ M’s College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.

It is estimated that as many as 2000 species of mammals, birds reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.

This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.

The entire procedure could take from three to five years to complete.

"The nuclear transfer of one species to another is not easy, and the lack of available(capable of being used) panda eggs could he a major problem," Kraemer believes. "They will probably have to do several hundred transfers to result in one pregnancy(having a baby). It takes a long time and it’s difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort," adds Kraemer, who is one of the leaders of the Project at Texas A ＆ M, the first-ever attempt at cloning a dog.

"They are trying to do something that’s never been done, and this is very similar to our work in Noah’s Ark. We’re both trying to save animals that face extinction. I certainly appreciate their effort and there’s a lot we can learn from what they are attempting to do. It’s a research that is very much needed. \

The aim of "Noah’s Ark" project is to （）.

A．make efforts to clone the endangered pandas

B．save endangered animals from dying out

C．collect DNA of endangered animals to study

D．transfer the nuclear of one animal to another