あんな習慣が最初にいつ生まれたのかは誰にもわからない。の英語

No one knows when such a custom first came into existence.

No one knows when such a custom came into existence.

No one remembers when it started.

No one remembers when it began.

No one knows how it came to pass.

No one knows how to it came to pass.

It is not known who made them, how, or for what reason.

No one can understand how the accident happened.

it is not known who created this piece

No one knew for certain how the accident happened.

No one knows what became of him.

Nobody is yet sure when robots will become common in our homes.

No one knew for certain how the accident happened.

What'll actually happen is anyone's guess.

What will actually happen is anyone's guess.

That custom has long been done away with.

Nobody could explain how the thing was made.

I have never heard of such a strange custom.

Nobody knows what may happen.

Nobody knows what has become of him.

No one can say for sure how this awkward state of affairs came about.

You can't expect a man to change his habits at once, girl.

No one knew for certain how the accident happened.

No one knows what happened at that time.

No one knows what happened then.

Nobody knew what the machine was like.

No one knows what has become of her.

No one knows how many people died in that war.

None of us knows what is in store for us.

Human beings seem to find it difficult to give up their old habits.