Possible to choose opening for computer to play on Chess.com?

I found that I when I play the Chess.com computer on a low level (I'm a beginner), and I open as white with e4, the computer chooses a defense seemingly at random.  By turning on coach mode I can feedback on my moves, see what the best/book moves are, etc.

I find this extremely valuable , but..

Is it possible to tell the computer which defense to use?

Or is this even the best way to practice openings? I've tried to get my head around Opening Explorer, but it isn't as interactive, and only seems to allow clicking through moves to a certain depth. 

(Also, I appreciate that as a beginner I should be focusing on fundamentals rather than openings, so if all you're planning to do is lecture me on that point, I get it, thanks.)

No, otherwise people might be tempted to use that program on the side while supposedly playing other people, if you know what I mean.

@Sqod I am not sure your argument is sound. If people want to cheat (God knows what for), they will find a way. Whether or not Chess.com has mechanisms to facilitate that or not will make no difference. I too would appreciate a facility to learn faster by practising the same opening defence responses over and over.