是可数名词。
n. 难题引起麻烦的人
adj. 成问题的难处理的Lawlessness is a major problem.
违反法律是一个严重的问题。
The problem is well documented.
这个问题有很多依据。
We seem to have hit a problem.
我们似乎遇到了问题。
She's a good problem solver.
她是解决问题的高手。
It's a bastard of a problem.
那是个挺麻烦的问题。
是可数名词,复数形式problems中文意思是[数]问题难题(problem 的复数)
We have encountered major problems.
These problems are closely related.