已知椭圆x2a2+y2b2=1(a>b>o)的左焦点为F(-2,0),离心率e=

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问题:

已知椭圆
x2
a2
+
y2
b2
=1(a>b>o)
的左焦点为F(-
2
,0),离心率e=
2
2
,M、N是椭圆上的动点.
(Ⅰ)求椭圆标准方程;
(Ⅱ)设动点P满足:
OP
=
OM
+2
ON
,直线OM与ON的斜率之积为-
1
2
,问:是否存在定点F1,F2,使得|PF1|+|PF2|为定值?,若存在,求出F1,F2的坐标,若不存在,说明理由.
(Ⅲ)若M在第一象限,且点M,N关于原点对称,点M在x轴上的射影为A,连接NA 并延长交椭圆于点B,证明:MN⊥MB.
考点:椭圆的标准方程及图象圆锥曲线综合
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葡萄糖酸锌的化学式为C12H22O14Zn(相对分子质量为455).试回答:

(1)葡萄糖酸锌是由______种元素组成的.

(2)葡萄糖酸锌中所含锌元素的质量分数为______(计算结果精确到0.1%)

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Like a scene out of a reality show or a Disney movie, Southgate, Mich., teenager Ashley Qualls' moment has arrived.

She may not have an MBA, a high-school diploma, or even a driver’s license yet, but Asheley Qualls already has an influential website (www. Whateverlife.Com). The 17-year-old girl hass been building her online business for two years.

In December 2004, Qualls borrowed $8 from her mother to buy the Whateverlife.com. domain name (域名). She intended to use the website as a way to share her design for My Space pages woth her friends.

But in the incontrollable, fast-moving world of cyberspace, others began noticing Qualls’ site even though she never has spent a penny on advertising.

When it comes to web traffic, Whateverlife.com .currently ranks No. 825 out of 20.3 million websites, drawing 2.4 million visitors worldwide during the last 30 days. Qualls said that on average, 72% of her site's audience made a return visit.

Whateverlife.com earned a million dollars in revenue last year and is on track to do the same this year.

"I'm stubborn and I'm independent," she said from her office in the basement of her house. "I like the feeling that it's my company, and I want to have the say-so (主张)in everything."

But don’t mistake Qualls for another smart but spoiled teenager. She is growing up fast but owns talent for life and business that elude many girls of her age.

The task of running a million-dollar company isn’t without its sacrifices( 牺牲) and challenges for a teenager. Qualls dropped out of Lincoln Park High School after her sophomore year to work fulltime on Whateverlife.com, a decision that she said shocked her family, friends and teachers . She now is studying to get her degree in graphic design.

小题1:Many people noticed Qualls’ site because_____________________.

A.it was set up by a 17-year-old girl

B.Qualls shares her design with her friends

C.Qualls has been building her online business

D.the world cyberspace develops fast and uncontrollable小题2: Which of the following statements is NOT true according to the text?

A.Qualls’ Website Whateverlife .com. No. 825 in 20.3 million websites.

B.About 2.4 million visitors worldwide visit her website every month.

C.Most of her audience have visited her website at least twice.

D.Qualls has the right to decide everything in her company.小题3:The underlined word “elude” in the 8th paragraph means_______________.

A.avoid

B.embarrass

C.exceed

D.encourage

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你是一名工程师,要负责设计建设一座核电站,你认为在核电站的建设地点选取上最应该注意什么问题?为什么?

题型:解答题

体液的pH影响药物转运是因为它改变了药物的()

A.稳定性

B.脂溶性

C.pKa

D.离解度

E.溶解度

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什么是免疫球蛋白?什么是抗体?

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