touch on something
touch upon something

President Bush does touch on the world once in a while.

The play may be seen to touch on all of these issues.

However, I would like to touch on a few points.

I would like to touch on three of them, each in turn.

Finally, I would like to touch on a general matter.

I would like to touch on a few of these.

She had to come back and touch him on the arm.

In other words, we didn't touch on the subject again.

I just want to touch on two other points he raised.

Let me touch, also, on a couple of the specific issues about which I was asked.