Authenticating with public key "imported-openssh-key"

i use scripting to login sftp
but always stop in here
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! 2009-09-18 14:38:46.312 Authenticating with public key "imported-openssh-key"
. 2009-09-18 14:38:46.312 Prompt (2, SSH key passphrase, , Passphrase for key "imported-openssh-key": )

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how can auto input the key ??

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