Proper use of 了 in Chinese

Question

For my Chinese language class, I need to go through this practice worksheet and fill out which uses of 了 are correct. However, while I think I know decently when to use 了， I am not sure about some of my answers, as we have not discussed some things in class.

| 我们现在一起吃饭了。 | I'm not sure about this one. I think it might be correct because it could say "Now we can eat," which uses 了 to indicate a change.
| | 我明天要跟你去健身房了。 | I don't think this one is correct because it uses 明天 and 要which indicates it will happen in the future. |

| 我已经吃了午饭。 | I think this one is correct, it says "I already ate lunch." |

| 我看电影了。 | This one seems correct, "I watched TV." |

| 她穿新的裙子了 | This one also seems to use 了correctly, it says "She wore a new skirt." | | 我去了中文课了。 | Again, this one also seems to use 了 correctly, I believe it translates to "I have been going to Chinese class." | | 他会说中文了。 | This one also seems correct. "He can now speak Chinese." |

| 你真的买了两个新的电视吗？ | I also think this is correct, because the 了 occurs before the numbers and indicates a the past tense of 买。 “Did you really buy two televisions?" |

| 他买四本书了 | This one isn't correct because 了occurs after the quantity and not before the quantity and after the verb like it should. |

| 你们回家了 | I think this one is correct, it translates to "You have returned home." |

Answer 1

I got this from another forum, I find it useful:

了和过的区别

了和过都能用在动词后面。 了 有表示过去时，现在进行时，将来时的意思。 如：我去了一趟超市。（过去） 我睡觉了。（现在）
我到了给你打电话。（将来）
过 只表示过去发生的某些事情。不能表示现在时和将来时。
如：我去过中国。

了 和 过的用法是非常相似的，希望你能慢慢体会，多多练习。(ง •_•)ง,加油

My take on your sentences:

1. 我们现在一起吃饭。

2. 我明天要跟你去健身房了。

3. 我已经吃了午饭。

4. 我看电影了。

5. 她穿了新的裙子。

6. 我去了中文课了。（第二个‘了’是语气助词）

7. 他会说中文了。

8. 你真的买了两个新的电视吗？

9. 他买了四本书。

10. 你们回家吧。

Answer 2

我明天要跟你去健身房了 and 我明天要跟你去健身房 are not the same mean.

我明天要跟你去健身房了。 means in the past, I didn't need to go to gym, while I have to do it tomorrow.

我明天要跟你去健身房。 it has nothing related to the past, just means that I will do that tomorrow.