根据首字母或汉语提示写出单词

1. The policeman made a polite g_______ at the driver to stop the car.

2. We couldn’t have a picnic because of the s_______ change in the weather.

3. B________ is thicker than water.

4. The children stood _________ (不动)and watched as the deer came closer.

5. It's very _______ (安静的)out here in the woods.

明矾石的主要成分为K₂SO₄·Al₂(SO₄)₃·2Al₂O₃·6H₂O，此外还含有少量Fe₂O₃杂质。某校研究小组利用明矾石制备氢氧化铝的流程如下：

(1)“焙烧”过程中反应的化学方程式为Al₂(SO₄)₃＋SAl₂O₃＋________↑。

(2)分离溶液和废渣的操作是________，“溶解”时反应的离子方程式为_________________________________。

(3)“调节pH”后过滤、洗涤Al(OH)₃沉淀，证明沉淀已洗涤干净的实验操作和现象是________。

(4)“母液”中可回收的物质是________。

(5)若“焙烧”过程中恰好消耗48 g硫黄，则理论上最终可得到________ g氢氧化铝。