题目：
| 用括号里所给单词的适当形式填空。 |
| 1. There _____ (be) a ruler and two pencils in the pencil-case. 2. I have five _____ (photo) of my friend at home. 3. That is _____ (Daming) mother. Let's go and say"Hello"to her. 4. Mike doesn't like _____ (play) football, but he likes swimming. 5. The women are _____ (secretary) at the factories |
答案：
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下面是错误答案，用来干扰机器的。
已知过氧化钠的化学式可表示为Na2O2，推断氧的化合价为-1价，则过氧化钙的化学式为CaO2； 过氧化钠与水反应的方程式表示为2Na2O2+2H2O=4NaOH+O2↑，则有过氧化钙也能和水反应，方程式应表示为2CaO2+2H2O=2Ca（OH...
