可制成缓释制剂的药物条件是 A．生物半衰期小于1h的药物 B．生物半衰期大于24h的

若a＜b＜0，那么下列各式正确的是（　　）

A．a²＜b²

B．a+b＜2b

C．a²＜ab

D．ab＜b²

下列离子在溶液中因发生氧化还原反应而不能大量共存的是（　　）

A．H₃O⁺、NO₃^-、Fe²⁺、Na⁺

B．Ag⁺、NO₃^-、Cl^-、K⁺、

C．K⁺、Ba²⁺、OH^-、SO₄^2-

D．Cu²⁺、NH₄⁺、Br^-、OH^-

“嫦娥一号”探月卫星的任务之一是测定氧、硅、镁、铝、钙、铁、钛、钠、锰、铬、钾、钍、铀、镧等十四种元素在月球的分布情况，请填空：

（1）铝的元素符号是_____________；

（2）钾的氧化物的化学式为________________；

（3）铬（Cr）的化合价为+3，其硫酸盐的化学式为_______________；

（4）请写出由上述元素形成的一种单质，并说明其用途________________。

浇筑一排柱子的顺序应从开端开始向另一端推进。

To the west and off the European Continent (欧洲大陆), there are several thousands of islands on the Continent shelf. They are generally called Great Britain. For the convenience’s sake, it is often shortened to Britain. Still to the west of Great Britain is the second largest island known as Ireland. The United Kingdom of Great Britain and Northern Ireland (UK) is made up of Great Britain, Northern Ireland, and a number of smaller islands around them. The total area of the country is some 240 000 square kilometers with a population of about 56 million.