仔细观察下面的图形算式，相同的图形代表相同的数．○、△、□代表几？

（1）□+□+□+△+△=23

（2）□+□+△+○=17

（3）○+○+□+△=15

□=____○=____△=____．

根据短文理解，从A、B、C、D四个选项中选择最佳填空。

    Hi, my name is Dave. I'm 8 1 old. My birthday is 2 December 12th. I have 3 birthday party every year. Today I have my 4 birthday party. I get some gifts at the party. 5 are very good and I really like them. This 6 T-shirt is from my mother. Green is my 7 color. My mother buys me a pair of green 8, too. My father buys some 9 about history for me, because I like 10 best. I think these books 11 very interesting. My grandparents 12 I like playing basketball, 13 they buy me a basketball. I can 14 it with my friends after class. I'm very happy today.

    15 is your birthday, my friend? Do you have a party, too?

通过学习碱的性质，我校化学兴趣小组的同学对实验室的“氢氧化钙是否变质以及变质的程度”展开了探究活动，请你一同参与：（氢氧化钙变质生成碳酸钙，碳酸钙不溶于水．）

Ⅰ．提出问题：氢氧化钙是否变质？

Ⅱ．猜想与假设：同学们经过讨论认为样品存在三种可能情况：没有变质；部分变质；完全变质．

Ⅲ．实验探究：

Ⅳ．小结与思考：

小蔓同学根据上述实验方案进行实验，确定该样品已部分变质，请写出实验中反应的化学方程式（只要求写一个）：____ ．