Question

be beneficial to还是for？

Answer 1

都可以。只能用for的情况 ：be beneficial for somebody to do sth. 其他的for/to sb/sth 可以任意用，都是没错的，不过to是标准搭配。

beneficial　

英 [ˌbenɪ'fɪʃl] 　美 [ˌbenɪ'fɪʃl] 　 　

adj. 有利的；有益的

It's a beneficial result to us.

对我们来说那是有利的结果。

近义词

good　

英 [ɡʊd] 　 美 [ɡʊd] 　 　

adj. 好的；上等的；优秀的

n. 好处；善行

My one good suit is at the cleaner's.

我那套讲究的衣服还在洗衣店里呢。

Answer 2

只能用for的情况 ：be beneficial for somebody to do sth。

其他的for/to sb/sth 可以任意用，不过to是标准搭配。
例句

1、I think it would be beneficial for each committee member to have a copy of the report.

2、 Lowering salt intake has a beneficial effect on blood pressure.

3、Relaxation classes can be beneficial to people of all ages.

4、Work experience is usually highly beneficial for students.