英语"他一定受过专门培训"

He must have been trained specially.
一方面强调对现在造成的影响，所以用现在完成时；另一方面，表示语气较为肯定的推测，所以用must

He must be professionally trained(接受过职业化的培训)
He must be specially trained 也可以

He must be trained specifically.

He must be specially trained