Pause and listen
Let's be honest: Do you really listen to what your customers have to say, or are you just catching your breath between questions?
Source: Sales consultant Colleen Francis
If that sounds a little too familiar, try counting silently to three (at a regular speaking pace!) every time your prospect finishes talking.
This will give them enough time to gather their thoughts and continue what they were saying if they haven't finished, while also not being a long enough pause to seem awkward if they are done talking, and are simply waiting for your response.