a problem of great urgency的用法和样例：
- We are facing a problem of great complexity.
- This is a matter of great urgency.
- Such logic two hundred years ago would have prevented expansion westward past the Appalachian Mountains, for assuredly the Eastern Seaboard was beset by problems of great urgency then, as it is today.
- It's a problem of such perplexity that it was impossible to solve.