He is so closely hemmed in on all sides that I doubt whether he could escape even if he grew a pair of wings.

密密层层的天罗地网，我看他插翅难飞。

《新英汉大辞典》

If you haven't got a degree or diploma in engineering I doubt whether all the King's horses and all the King's men could get you a job with that particular firm.

如果你没有工程学位或毕业证书，我想没人能帮助你搞到该公司的工作。

youdao