To do many things at the same time, such as driving and phone talk makes waste concentrate on driving through an accident, that we do not think it is at the most, I think we should not do anything together at the same time.
What to do many things at once, for example. Driving and talking on the phone distracting the driver caused the accident, we do not assume any rate, the more I think we should do the same at the same time.
To do things at the same time as. Driving and talking on the phone, the distraction of the drive until the accident that we do not think the rate as much as I think people should not do at the same time at the same time.