4條英文語感問題

1. Can you three ride on a bicycle?

you three= three of you, but three of you sound more formal

2. Do you know the reason why they love each other?

It will be more natural to not add for

3. Let us three go together is not 請求比我地三個一齊去啦
Please let us go together =請求比我地三個一齊去啦

Let's three go together does not mean 我地三個一齊去吧
It should be: Let the three of us go together.

4. I don`t think both are natural.
It should be: When he was young, he was not not happy.

同意批卷貓所講，但Can you three ride on a bicycle? 同 Can you three ride on bicycles? 邊句先啱？

係咪應該講成 Can one of you three ride on a bicycle? 先至最恰當？

1.Can all three of you ride on a bicycle?

or (your are talking to all three of them so no need to say all three of you

Can all of you ride on a bicycle?

2.Do you know the reason why they love each other?

3.Let us all (all three of us) go together.

Please let us all ( all three of us) go together.

4.When he was young, he was not happy
or
He was not happy when he was young.

The followings are the corrected sentences as required:
(1)"你地三個識唔識踩單車？"
Translation: Do three of you know how to ride bicyle?
you three does not equals to three of you;
(2) reason..........why..........; or reason..........why,,,,,,,for
Do you know the reason why they love one another?
Do you know the reason why you and I love each other?
(3)"請求比我地三個一齊去啦"？
Will you please let three of us go out together?
(4) During his young age, he was rather unhappy.

you three = 你們三個，　你們 = 三個

three of you = 你們其中三個，　你們 ≥ 三個