将普通句子改为一般疑问句，需根据句子结构和动词类型进行相应调整，具体规则如下：

一、基本结构规则

含be动词的句子

将be动词（am/is/are/was/were）提前至句首，后续接主语和其余部分。 - 例：

- This is a teacher's desk. → Is this a teacher's desk？

- These are my dictionaries. → Are they your dictionaries？

含情态动词的句子

将情态动词（can/must/need/will/can't等）提前至句首，后续接主语和动词原形。 - 例：

- I can run fast. → Can you run fast？

- She must finish her homework. → Must she finish her homework？

含实义动词的句子

在主语前添加助动词do/does/did，将原形动词置于主语之后。 - 例：

- I like cakes very much. → Do you like cakes？

- He went to the park yesterday. → Did he go to the park yesterday？

含have/has/had的句子

将have/has/had提前至句首，后续接主语和动词原形（have作"有"解时也可提前）。 - 例：

- I have a cat. → Do you have a cat？

- She had lunch at 12 PM. → Did she have lunch at 12 PM？

二、注意事项

be动词与情态动词的区分

- be动词：am/is/are/was/were

- 情态动词：can/must/need/will/can't等

若句子中已包含be动词或情态动词，则无需再加助动词。

特殊疑问句的转换

若需询问具体成分（如时间、地点），需先改为一般疑问句，再添加疑问词（如what, where, when等）。 - 例：

- I'll call you later. → When will I call you later？

缩写形式的使用

助动词和情态动词的否定形式可用缩写（如don't, doesn't, didn't），但be动词的否定需完整书写（如isn't, aren't）。

三、示例总结

| 陈述句 | 一般疑问句 | 肯定回答 | 否定回答 |

|--------|--------------|----------|----------|

| This is my book. | Is this my book？ | Yes, it is. | No, it isn't. |

| She can sing beautifully. | Can she sing beautifully？ | Yes, she can. | No, she can't. |

| They have finished their homework. | Have they finished their homework？ | Yes, they have. | No, they haven't. |

通过以上规则，可系统地将普通句子转换为一般疑问句，并根据需要调整时态和人称。