Looking on the internet deeply has found these results:

I can be of great help to you. is the most popular phrase on the web.

I can be of a great help to you. 17 results on the web	I can be of great help to you. 11,070,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	I think they can be of great help. The developing countries naturally need regulations that provide a legal framework, and perhaps this is an area in which the EU can be of great help to the developing countries. I know I can be of great help to the ship. While the words can be of great help. Colonel Sheppard believes you can be of great help to us. I will be of great help to you Mr. Quatermain. I would note that the first thing that the country needs to do is to draw up its constitution, and Europe can be of great help in this.

I can be of a great help to you.

17 results on the web

I can be of great help to you.

11,070,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

I think they can be of great help.
The developing countries naturally need regulations that provide a legal framework, and perhaps this is an area in which the EU can be of great help to the developing countries.
I know I can be of great help to the ship.
While the words can be of great help.
Colonel Sheppard believes you can be of great help to us.
I will be of great help to you Mr. Quatermain.
I would note that the first thing that the country needs to do is to draw up its constitution, and Europe can be of great help in this.