所有的等腰三角形都是锐角三角形．______．（判断对错）

在H₂SO₄溶液中分别滴加（或加入）少量的下列溶液（或物质）：写出反应的现象和有关的离子方程式。 ①CH₃COONa溶液____________________

②氨水____________________

③Cu(OH)_{2_____________________}

④Zn粒____________________

⑤Fe₂O₃粉末_______________________。

阅读下面有关毒奶粉中导致婴儿 * * 结石的“三聚氰胺”的信息，回答问题：

2008年9月，中国爆发三鹿婴幼儿奶粉受污染事件，导致食用了受污染奶粉的婴幼儿产生肾结石病症，其原因是奶粉中含有三聚氰胺．三聚氰胺性状为纯白色单斜棱晶体，分子式C₃N₆H₆，无味，密度1.573 g/cm³（16℃）．常压熔点354℃（分解）；快速加热升华，升华温度300℃．溶于热水，微溶于冷水，极微溶于热乙醇，不溶于醚、苯和四氯化碳，可溶于甲醇、甲醛、乙酸、热乙二醇、甘油、吡啶等．低毒．在一般情况下较稳定，但在高温下可能会分解放出氰化物，氰化物通常具有毒性．

（1）请总结三聚氰胺的物理性质（各写一点）：______；化学性质：______；

（2）三聚氰胺属于______（填“混合物”或“纯净物”）；三聚氰胺的相对分子质量：______．

Miss Gorgers taught physics in a New York school. Last month she explained to one of her classes about sound, and she decided to test them to see how successful she had been in her explanation. She said to them, “Now I have a brother in Los Angeles. If I was calling him on the phone and at the same time you were 75 feet away, listening to me from the street, which of you would hear what I said earlier, my brother or you and for what reason?”

Tom at once answered, “Your brother. Because electricity travels faster than sound waves.” “That’s very good.” Miss Gorgers answered, but then one of the girls raised her hand, and Miss Gorgers said, “Yes? Kate.”

“I disagree. Your brother would hear you earlier because when it’s 11 o’clock here and it’s only 8 o’clock in Los Angeles.” Kate said.

小题1:

Miss Gorgers was teaching her class         .

A．how to telephone

B．about electricity

C．about time zone

D．about sound小题2:

Miss Gorgers raised this question because she wanted to know whether         .

A．it was easy to phone to Los Angeles

B．her student could hear her from 75 feet away

C．her students had understood her lesson

D．sound waves were slower than electricity小题3:

Kate thought Tom was wrong because         .

A．clocks in Los Angeles showed a different time from those in New York

B．electricity was slower than sound waves

C．Tom was not good at physics at all

D．Tom’s answer had nothing to do with sound waves小题4:

Whose answer do you think is correct according to the laws of physics?

A. Tom’s.   　 　 B. Kate’s.        C. Both A and B. 　 　D. Neither A nor B.

如果两个朋友已相识多年，他们之间的情感必然非常（）；有时亲密无间，有时形同陌路。潮起潮落，甘甜苦涩。我们如何平静地对待这些起起落落，直接影响到友谊的（）。依次填入括号处的词语，最恰当的一组是（）。

A.深厚；发展

B.复杂；进展

C.细腻；保持

D.多样；延续

起吊过程中必须设专人监护。