△ABC中,∠ACB=90°,∠A=30°,CD⊥AB于D,则AD:DB=___

题型:填空题

问题:

△ABC中,∠ACB=90°,∠A=30°,CD⊥AB于D,则AD:DB=______.

考点:直角三角形的性质及判定
题型:填空题

阅读理解。

     With only about 1, 000 pandas left in the world, China is desperately trying to clone (克隆) the animal and

save the endangered species (物种). 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 (胚胎), 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 2, 000 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 (核子移植) of one species to another is not easy, and the lack of available panda eggs

could be 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."

1. 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

2. According to Professor Kraemer, the major problem in cloning pandas would be the lack of _____.

A. available panda eggs

B. host animals

C. qualified researchers

D. enough money

3. Which of the following should be the best title for the passage?

A. China's Success in Pandas Cloning

B. The First Cloned Panda in the World

C. Exploring the Possibility to Clone Pandas

D. China -the Native Place of Pandas Forever

4. From the passage we know that _____.

A. Kraemer and his team have succeeded in cloning a dog

B. scientists try to implant a panda's egg into a rabbit

C. Kraemer will work with Chinese scientists in clone researches

D. about two thousand of species will probably die out in a century

题型:填空题

男,48岁,呼吸困难、胸痛,结合CT图像,最可能的诊断是()

A.支气管胸膜瘘

B.肺结核

C.吸入性肺炎

D.肺囊虫病

E.肺脓肿

题型:填空题

梨园是( )朝宫廷设置的专门训练乐工的机构。

A.清

B.元

C.宋

D.唐

题型:填空题

用行驶里程作为汽车使用寿命的量标,比较客观地反映了汽车的()

A.使用频率

B.使用条件

C.停驶闲置期间的自然损耗

D.使用强度

题型:填空题

高度重复序列有哪些各有什么特点

更多题库