Believe it or not, I've had ....
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You will find this hard to believe, but I've already ....
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You may not believe me, but I haven't had ..... since ....
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You may not believe this, but I've never been to ...
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You'll never believe this, but I've always liked ....
....
I know it's hard to believe, but I've never ....
....
This may seem hard to believe, but I've been to .....
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You'll find this hard to believe, but I've always been interested in ...
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This may sound unbelievable, but I've .....
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This may seem hard to believe, but I've never liked ....
....
Would you believe, I've never had ....
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