做某事有问题problem后面加不加s?如果换成trouble或difficulty呢?

这三个字加不加S要看你指单数还是复数.另外,有一两个习惯用法是只用单数的：如got in trouble with the police.
I've had troubles ever since I took this job.
A cause or source of distress,disturbance,or difficulty:The new recruits were a trouble to him.
这种情况不不用复数.