useful和helpful的区别如下：helpful 有帮助的

useful 有用的

Role-play is helpful in developing communication skills.

角色扮演有助于提高沟通技巧。

You are very helpful.

您真帮了我的大忙。

These things are helpful for my life.

而且对我的生活是有帮助的。

These tactics are unlikely to be helpful to you.

这种方法对你未必有用。

The experience in army is helpful to him.

他从军的经历对他很有用。