The phrase "understand precisely" is correct and usable in written English.
You can use it when you want to emphasize that someone understands the details of something. For example: "He was able to understand the financial regulations precisely and develop a plan accordingly."
We all know H2O, even if we don't understand precisely what it means.
The city's fabled political machine has faded and shifted, and Mr. Emanuel may be the first to understand precisely how.
Yet because AIG pools its results from foreign operations, it is difficult to understand precisely how, and where, it makes money.
Go back to your countries, get real with your governments, and get the people of your age group to understand precisely what happens.
Over the last few weeks, I have sought to understand precisely what the banks committed to doing and how much progress they are making.
As Alia explained, if they can understand precisely how a protein works, they might be able to understand why in some cases -- like Alzheimer's -- it malfunctions.
Dr. Astaneh-Asl hopes to conduct what is, in essence, an autopsy of the buildings felled by the terrorist attacks, to understand precisely how they fell apart.
There is usually a party on the pitcher's mound in late October and you have to be out there to understand precisely how it feels.
He urged the judges to pore over the same material, and predicted "you will understand precisely, as Judge Ware did, why this case can't be litigated".
But then, he was talking to the Anglican Communion, so they would be able to understand precisely with what he's saying.
Johnson will understand precisely what he means, but will expect every English tight forward to show his mind is on the job between now and the World Cup.
