啤酒酒花的主要成分及啤酒花的作用是什么？

根据所给信息写出对应的单词及与它发音相同的大写字母。

1.  _____________  _____________

2.  _____________  _____________

3.  _____________  _____________

4.  _____________  _____________

5.  _____________  _____________

6.  _____________  _____________

“三无”老人是指无劳动能力、无生活来源、( )的老年人。

A．无子女

B．无居住场所

C．无固定职业

D．无生活自理能力

E．无赡养人和扶养人(或赡养人和扶养人确无赡养和扶养能力)

某化合物中H、S两元素的化合价为+1、－2，该化合物的化学式是

A．

B．

C．

D．

建设部,国家文物局请示国务院,国务院办公厅:　　前年,国务院批准了21个城市为国家历史文化名城,这对制止建设性破坏,保护城市传统风貌起了重要作用.不过除已批准的国家历史文化名城外,还有一些城市古迹十分丰富,……按照国发(1986)104号文关于审定国家历史文化名城的原则,进行反复酝酿,提出37个城市,建议作为第二批历史文化名城(名单附后)……　　请即批转各地区,各部门研究执行.　　附件:第二批国家历史文化名城名单　　第二批国家历史文化名城简介　　另,建设部和国家文物局拟成A-L保护历史文化名城联署办事小组,如无不妥,请批准.　　建设部,国家文物局　　1993年6月10日

The human Y chromosome—the DNA chunk that makes a man a man—has lost so many genes over evolutionary time that some scientists have suspected it might disappear in 10 million years. But a new study says it’ll stick around.
Researchers found no sign of gene loss over the past 6 million years, suggesting the chromosome is "doing a pretty good job of maintaining itself," said researcher David Page of the Whitehead Institute for Biomedical Research in Cambridge, Mass.
That agrees with prior mathematical calculations that suggested the rate of gene loss would slow as the chromosome evolved, Page and study co-authors note in Thursday’s issue of the journal Nature. And, they say, it clashes with what Page called the "imminent demise" idea that says the Y chromosome is doomed to extinction.
The Y appeared 300 million years ago and has since eroded into a dinky chromosome, because it lacks the mechanism other chromosomes have to get rid of damaged DNA. So mutations have disabled hundreds of its original genes, causing them to be shed as useless. The Y now contains only 27 genes or families of virtually identical genes.
In 2003, Page reported that the modern-day Y has an unusual mechanism to fix about half of its genes and protect them from disappearing. But he said some scientists disagreed with his conclusion. The new paper focuses on a region of the Y chromosome where genes can’t be fixed that way.
Researchers compared the human and chimpanzee versions of this region. Humans and chimps have been evolving separately for about 6 million years, so scientists reasoned that the comparisons would reveal genes that have become disabled in one species or the other during that time.
They found five such genes on the chimp chromosome, but none on the human chromosome, an imbalance Page called surprising. "It looks like there has been little if any gene loss in our own species lineage in the last 6 million years," Page said. That contradicts the idea that the human Y chromosome has continued to lose genes so fast it’ll disappear in 10 million years, he said. "I think we can with confidence dismiss … the ’imminent demise’ theory," Page said.
Jennifer A. Marshall Graves of the Australian National University in Canberra, a gene researcher who argues for eventual extinction of the Y chromosome, called Page’s work "beautiful" but said it didn’t shake her conviction that the Y is doomed.
The only real question is when, not if, the Y chromosome disappears, she said. "It could be a lot shorter than 10 million years, but it could be a lot longer," she said.
The Y chromosome has already disappeared in some other animals, and "there’s no reason to expect it can’t happen to humans," she said. If it happened in people, some other chromosome would probably take over the sex-determining role of the Y, she said.

It can be inferred from the first 3 paragraphs that
[A] the human Y chromosome has stopped evolution.
[B] a man will no longer be a man in 10 million years.
[C] scientists are divided on the latest issue of Y chromosome.
[D] mathematical calculations are important in genetic studies.