直角三角形两直角边长分别为6cm，8cm，则其斜边上的高为（ ）cm。

患者无牙颌，下颌牙槽嵴低平，上颌颌弓小于下颌弓，制作传统全口义齿防止脱位应注意（）。

A.上、下人工牙应排列在牙槽嵴上

B.下颌基托范围尽量伸展

C.选用解剖式人工牙

D.选用金属基托

E.垂直距离适当降低

碳酸氢钠常用于食品和医药工业，某化学兴趣小组对碳酸氢钠进行探究。

【查阅资料】 Ⅰ．碳酸氢钠受热容易分解，生成水、二氧化碳气体和一种常见的固体物质。

Ⅱ．碳酸钠溶液呈碱性。

【进行实验】为了验证碳酸氢钠受热时会分解，兴趣小组的同学取一定质量的碳酸氢钠到铜片上加热，如图所示。

（1）加热一段时间后，观察到烧杯内壁有__________。

（2）充分加热后，将烧杯迅速倒转过来，倒入适量的澄清石灰水，振荡，观察到石灰水变浑浊。写出该反应的化学方程式：___________________。

（3）兴趣小组的同学认为：充分加热后的固体产物可能是NaOH或Na₂CO₃。

①他们的依据是____________________________________。

②兴趣小组为了确定反应后的固体产物成分进行以下实验，请填写下表：

实验	实验现象	结论
实验一：取少量反应后的固体产物溶于水，滴入几滴酚酞试液	溶液变成红色	固体产物是NaOH，而不是Na2CO3
实验二：取少量反应后的固体产物溶于水，加入氯化钙溶液	_____________	固体产物是Na2CO3，而不是NaOH
实验三：___________________ ___________________________	产生大量气泡	固体产物是Na2CO3，而不是NaOH

 

【讨论与评价】实验一的结论与实验二、实验三的结论相反，在讨论时兴趣小组的同学认为方案一的结论不正确，他们的理由是_____________________________________________。

【总结】请写出碳酸氢钠受热分解的化学方程式________________________。

（4）某碱厂的主要产品之一是小苏打（碳酸氢钠），为了测定产品中碳酸氢钠的质量分数（假设该样品中只含氯化钠一种杂质），取样品10．0 g逐滴加入稀盐酸，所得气体的质量为4．4 g。求：样品中碳酸氢钠的质量分数。

实际工程中，为了计算方便可假设变压器额定电压下的空载损耗等于铁损耗，它随着负载变化而变化。

由于某种原因，种群进入新地区后得到迅速扩展蔓延，称为______。

Blair Admits Never Having Sent Flowers to His Wife

British Prime Minister Tony Blair admitted on a television programme that he has never sent flowers to his wife Cherie and that he had a youthful crush on Hollywood beauty Grace Kelly.
Blair, who allowed Channel 4 interviewer June Sarpong to shadow him for two days last month, made other personal (1) when asked questions he rarely hears on the usual television political (2) .
During the interviews for a program targeting 18-30 year (3) , the prime minister admitted he sometimes has to "wing it" when (4) public appearances and that he yearns to go out for a drink (5) being recognised.
However, the most dramatic revelation was his reply to Sarpong’s (6) on whether he still sends his wife flowers, prompting his interviewer to (7) in disbelief. "I’ve never sent her flowers. If I sent her flowers, she would (8) worried," Blair said.
But he added: "I am romantic. There are other ways of (9) romantic."
Blair needed a few moments to recall which posters he had (10) his bedroom wall as a youngster, then revealed: "I’ll tell you... actually, (11) I was younger, I loved Grace Kelly."
Born in 1929, Kelly (12) in films like ’Dial M For Murder’, ’Rear Window’ and ’High Society’ in the mid-1950s, but (13) acting to marry Prince Rainier of Monaco in 1956, when Blair was (14) two years old.
Blair admitted he initially found it "odd" to be (15) minister and to be rushed in motorcades from appointment to (16) , and worried that his lifesty left him "a bit isolated" from (17) people.
He admitted that he was constantly on the phone between public (18) , and rarely had time to prepare for his next (19) , telling Sarpong: "I wing it all the time."
And he revealed he has to check himself before he replies to (20) questions from the public. "The worst thing is when someone is giving you a real earful and you think ’I’m going to say something I will regret’," he said.
Asked what he would do if he could be invisible for a day, Blair yearned for a more ordinary life, saying he would "just walk down the street and go to the pub... just be absolutely normal".