Understanding how to use 可以 (kěyǐ) in Mandarin conversations is really important. It helps us talk about permission. This word can mean "can," "may," or "be allowed to." By learning how to use 可以 correctly, you’ll do a better job in conversations about what’s allowed or not.

Here are the main ways to use 可以:

1. Basic Structure: Subject + 可以 + Verb
   This is the simplest way to ask for permission. You just put the subject, then 可以, and then the action you want to do. For example:

• 我可以去吗？(Wǒ kěyǐ qù ma?)
  Can I go?
  In this sentence, “我” (I) is the subject, “可以” shows permission, and “去” (to go) is the action.

2. Adding Objects: Subject + 可以 + Verb + Object
   To say what you can do, you can add an object. For example:

• 你可以吃这个。(Nǐ kěyǐ chī zhège.)
  You can eat this.
  Here, “你” (you) is the subject, “可以” shows permission, and “吃这个” (eat this) tells us the action.

3. Questions with 可以
   When you ask a question, you still place 可以 the same way. To change a statement into a question, add “吗” (ma) at the end:

• 他可以来吗？(Tā kěyǐ lái ma?)
  Can he come?
  The sentence keeps the same order, with “来” (to come) being the action.

4. Negative Form: Subject + 不可以 + Verb
   To say that something is not allowed, use "不可以" (bù kěyǐ). For example:

• 我们不可以这样做。(Wǒmen bù kěyǐ zhèyàng zuò.)
  We cannot do it this way.
  This structure is like the positive one, but here we use 不可以 to say no.

5. Using Modifiers: Subject + 可以 + Adverb + Verb
   You can add information about how or when something is done using adverbs. For instance:

• 她可以慢慢走。(Tā kěyǐ màn màn zǒu.)
  She can walk slowly.
  The word “慢慢” (slowly) gives us more info about the action.

6. Expressing Conditions: Subject + 在 + Condition + 的时候 + 可以 + Verb
   To show when something is allowed, you can use this structure. For example:

• 在你完成作业的时候，我可以帮你。(Zài nǐ wánchéng zuòyè de shíhòu, wǒ kěyǐ bāng nǐ.)
  When you finish your homework, I can help you.
  This shows under what condition the permission applies.

7. Combining with Other Modal Verbs
   Sometimes, 可以 is used with other verbs to show what is allowed in certain situations. For example:

• 我能去，也可以参加派对。(Wǒ néng qù, yě kěyǐ cānjiā pàiduì.)
  I can go and am also allowed to attend the party.
  In this sentence, we use 能 (néng, can) with 可以 to explain permission and ability together.

In conclusion, getting the hang of these structures with 可以 will help you talk about permission in Mandarin. Practice these sentence patterns by making your examples. The more you use them, the easier it will be to understand and use this important part of Mandarin Chinese.