将陈述句“The baby is sleeping now”变为一般疑问句，可以通过以下几种方式实现：
1. 在句首添加疑问词
将句子变为一般疑问句最直接的方法是在句首添加疑问词。例如：
- Is the baby sleeping now?
- Is the baby sleeping?
- Are they sleeping now?
2. 将系动词改为be的一般疑问句形式
在句子中，系动词“is”可以改为其一般疑问句形式“are”，并将主语和be动词的位置颠倒。例如：
- The baby is sleeping now. → Is the baby sleeping now?
- The baby is sleeping now. → Are they sleeping now?
3. 在句尾添加助动词
在句尾添加助动词“is”或“are”也可以将陈述句变为一般疑问句。例如：
- The baby is sleeping now. → The baby is sleeping, isn't it?
- The baby is sleeping now. → The baby is sleeping, aren't they?
4. 使用否定词
在句首添加否定词“isn't”或“aren't”可以将句子变为否定的一般疑问句。例如：
- The baby is sleeping now. → Isn't the baby sleeping now?
- The baby is sleeping now. → Aren't they sleeping now?
5. 使用倒装句
将be动词和主语的位置颠倒，并添加疑问词或助动词，可以形成倒装句的一般疑问句。例如：
- The baby is sleeping now. → Is the baby sleeping now?
- The baby is sleeping now. → Are they sleeping now?
需要注意的是，当句子中的主语是第三人称单数时，be动词需要根据主语的人称和数来变化。例如：
- The baby is sleeping now. → Is the baby sleeping now? (主语是第三人称单数，所以be动词用is)
- The babies are sleeping now. → Are the babies sleeping now? (主语是第三人称复数，所以be动词用are)
掌握这些方法，可以帮助高考考生和家长在英语学习中更好地理解和运用一般疑问句。
