Joining of sentences - the secret/it

[kohyoongliat]

You must promise to keep the secret. I shall tell you the secret as long as you promise to keep the secret.

In joining the sentences, which of the following sentences is correct?

1. I shall tell you the secret as long as you promise to keep the secret.

2. I shall tell you the secret as long as you promise to keep it.

[LFulton]

I shall tell you the secret as long as you romise to keep it a secret.

[LFulton]

I shall tell you the secret as long as you romise to keep it a secret.

I shall tell you the secret as long as you promise to keep it a secret.

[Tdol]

You could also say 'as long as you promise to keep it secret'.