What's this? It's letter(字母)P. What colour is it? It's green. What's this and what colour is it? It's letter E. It's brown. What's this letter? It's letter N. It's red. P—E—N. Is it“pen”? Yes, it is.

    I have a blue pen in my pencil case(铅笔盒). My pencil case is orange. This is my book. It's my Chinese book. It's in my bag. My bag is black. Look! The bag is on the chair. The chair is yellow. It's my chair. It's nice. I like it.

被伊斯兰教、基督教和犹太教尊为“圣地”的是（  ）

用适当的数字和符号表示：

（1）地壳上含量最多的金属元素与最多的非金属元素组成的化合物____ ；

（2）3个二氧化氮分子　____ 　；

（3）2个铵根离子　____ ；

（4）火碱____ 　．