at great length的用法和样例：
- Standing at the bar he points them out to me, one by one, goes over them anatomically, describes their good points and their bad.
- He took imaginary cooking lessons from a Bohemian chef, who described in great detail how to slaughter a pig and use every part, from its trotters to the deboned hog's head.
- He talked at length about his work.
- There's no till to discuss the subject at large.