男性，26岁，2周前感冒，近日感胸闷，气急，心率100次／min，第一心音减弱，血沉

a，b，c成等比数列，那么关于x的方程ax²+bx+c=0[ ]

A．一定有两个不相等的实数根  

B．一定有两个相等的实数根  

C．一定没有实数根  

D．以上三种情况均可出现

对下列符号意义的表述，正确的是：

A．N₂两个氮原子

B．2H两个氢元素

C．2H₂O两个水分子

D．MnO₄^2-一个高锰酸根离子

阅读理解。

    As many as one in five US teenagers have some degree of hearing loss, according to researchers. They

say the problem is growing.

    Teenagers really don't pay attention to how much noise they are exposed (暴露) to, Josef Shargorodsky

of Brigham and Women's Hospital in Boston told Reuters. "Often people won't notice it, but even slight hearing

loss may affect language development," said Shargorodsky, one of the researchers.

    The study compared surveys from the early 1990s and the mid-2000s. Each included a few thousand

teenagers. In the first survey, about 15 percent of teenagers had some degree of hearing loss. Some 15 years

later, that number had risen by a third, to nearly 20 percent. 

    "This certainly is big news," said Alison Grimes, an ear doctor. Hearing loss is very common in old people,

Grimes said, but she added that it was worrying to see it happen in the younger age group.

    In babies and young children, hearing problems are known to slow language development. The science is

less clear for teenagers, but it is easy to imagine how being hard of hearing could affect learning, said Grimes. 

    The reasons for the rise are still unclear. When researchers asked teenagers about noise exposure-on the job,

at school or from activities, for example-the teenagers didn't report any change. But Shargorodsky said that

might not be true. "We knew from before that it is difficult to ask this age group about noise exposure-they

underestimate (低估) it." Few people would call it noise when they listen to music on their MP3 player, for

example. "There is a difference between what we think is loud and what is harmful to the ear," said Grimes. 

    Although it's not clear that the MP3 players cause teenagers' hearing loss, Grimes said it was still a good

idea to turn down the sound and take short breaks from listening.

1. According to the researchers, in a US class of 40 students, about _____ students have some degree of

    hearing loss. [ ]

A. one

B. five

C. six

D. eight

2. Which of the following statements is true according to the article? [ ]

A. Slight hearing loss does not influence learning.

B. Only a few old people have hearing problems.

C. Hearing problems can slow language development.

D. Noise exposure is clearly noticed by teenagers.

3. About hearing loss, it can be inferred that _____. [ ]

A. the reasons for the rise have been found

B. MP3 players are to blame

C. listening to loud music may be a cause

D. noise is the main reason

4. The article was written to _____. [ ]

A. warn teenagers that loud music might be harmful

B. explain what kinds of noises might affect studies

C. suggest that teenagers shouldn't listen to loud music

D. show how important hearing can be for learning

案情：2007年2月，甲乙丙丁戊五人共同出资设立北陵贸易有限责任公司（简称北陵公司）。公司章程规定：公司注册资本500万元；持股比例各20%；甲、乙各以100万元现金出资，丙以私有房屋出资，丁以专利权出资，戊以设备出资，各折价100万元；甲任董事长兼总经理，负责公司经营管理；公司前五年若有利润，甲得28%，其他四位股东各得18%，从第六年开始平均分配利润。至2010年9月，丙的房屋仍未过户登记到公司名下，但事实上一直由公司占有和使用。公司成立后一个月，丁提出急需资金，向公司借款100万元，公司为此召开临时股东会议，作出决议如下：同意借给丁100万元，借期六个月，每月利息一万元。丁向公司出具了借条。虽至今丁一直未归还借款，但每月均付给公司利息一万元。千山公司总经理王五系甲好友，千山公司向建设银行借款1，000万元，借期一年，王五请求北陵公司提供担保。甲说：“公司章程规定我只有300万元的担保决定权，超过了要上股东会才行。”王五说：“你放心，我保证一年到期就归还银行，到时候与你公司无关，只是按银行要求做个手续。”甲碍于情面，自己决定以公司名义给千山公司的贷款银行出具了一份担保函。戊不幸于2008年5月地震中遇难，其13岁的儿子幸存下来。北陵公司欲向农业银行借款200万元，以设备作为担保，银行同意，双方签订了借款合同和抵押合同，但未办理抵押登记。2010年5月，乙提出欲将其股份全部转让给甲，甲愿意受让。2010年7月，当地发生洪水灾害，此时北陵公司的净资产为120万元，但尚欠万水公司债务150万元一直未还。北陵公司决定向当地的一家慈善机构捐款100万元，与其签订了捐赠合同，但尚未交付。

北陵公司章程规定的关于公司前五年利润分配的内容是否有效？为什么？

FIDIC《施工合同条件》规定，( )只是表示承包商的施工义务终止，而合同约定的权利义务并未完全结束。

A．“结清单”生效

B．颁发履约证书

C．工程接收证书签发

D．提交竣工报告