The answer is because there's an etiquette to swearing which, though it changes constantly, remains ever present.
Creating accurate, targeted predictions about what an individual is like and their "inner demons", in a context where Facebook is also acting on that constantly, remains hard.
Nabokov would have been well advised to use it for it perfectly fits the general tone of his writing, both in Lolita and Ada, which is never vulgar, never makes use of crude words, and constantly remains at an eminent poetic or poerotic level.
For (R_{0}=1), it means that each infectious individual infects one other individual as a whole, then there is no change in the infected population, so the infection constantly remains in the population.
The phone jangles constantly; he remains placidly impervious.
Despite his many frustrations with the Israeli courts, Mr. Sourani says he remains "constantly amazed by the high standards of the legal system".
For all the sedulous care Kleist takes in presenting his stories as reasoned investigations into unreason (ghosts, possessions and apparent paradoxes recur) he remains constantly aware of the utility of drama, never averse to sudden changes in perspective or a confounding flurry of twists.
He constantly surprises me.
He constantly talks to people.
"He constantly criticized me".
This strange and brilliant man constantly invented and reinvented himself, and despite his voluminous writings, he remains an enigma.
