回答问题(简答)。

    Lucy is my good friend. She is eleven years old. She is a student. She likes singing. She has a nail pet. Her name is Kitty. Look, Lucy's singing and the cat is dancing. Lucy wants to be a singer when she grows up.

    Lucy's mother is a nurse. She works in a hospital. She likes shopping. She usually buys a lot of beautiful clothes at weekends.

要想对自己做出正确的评价，就要正视现实，实事求是，全面客观地看待自己。（   ）

请从给定化合价的五种元素中，选择适当的元素，按要求写出物质的化学式：单质 ____　；碱　 ____；可作为复合肥料的盐 ____　．