He had to hold back from shaking his head when Donna left his warning unheeded. Just like Lois had in the beginning. His wife eventually managed to kick the habit, something for which Kal was grateful. He knew that he'd inevitably outlive all the people he was close to. But if they stopped shortening their livespans deliberately it meant he'd have longer with them.
Donna didn't wave him off, so Clark leaned his shoulder against the wall, keeping a respectable distance between them, and took a sip of his coffee. The slightly confused response was to be expected he supposed, being unable to verbally communicate was difficult and he could see that while physically she appeared fine, mentally the day would be a challenge.
"I can't imagine work is very easy for you when you can't talk, but it's admirable that you still came in today."