hold (或 take) someone hostage

seize and keep someone as a hostage

把某人持為人質(zhì)

a hostage to fortune

an act, commitment, or remark which is regarded as unwise because it invites trouble or could prove difficult to live up to

招惹麻煩（或不明智、很難做到）的行為（或許諾、話語(yǔ)）擔(dān)風(fēng)險(xiǎn)

making objectives explicit is to &B{give a hostage to fortune}.

使目的明確就要承擔(dān)風(fēng)險(xiǎn)。