adobe illustrator - Automatically move its associated objects when move one object

In Adobe Illustrator, if we create a graphic figure with multiple related objects, we may want them move dependently. Let me show you a case:

I created a figure with 3 circles and 2 segments, the 2 segments connected the 3 circles on their centers. When I moved one of the circles, saying the middle, what I wanted was the 2 segments still connected its center. However currently the result is they seem independent with each other.

How can I make it work?

Answer

Choose Direct Selection tool (A) and make a selection as on this picture -

Result -

Now, click inside the circle and drag to desired location - the lines will move together with the circle.

You've done.