"This is impossible to comprehend."
Translation:Esto es imposible de comprender.
It is a bit more tricky than that. #1 imposible is not a verb. #2 There are eight verbs that my reliable grammar book list as needing DE if they are followed by an infinitive. Since 22 people to date thought your comment was worth an upvote, I will take the time to list them. It is great review for me too. The first one you will surely recognize because it is always taught in "Spanish 101" courses. Acabar de (to have just); accordarse de (to remember to); alegrarse de (to be glad to); cansarse de (to be tired of); dejar de (to stop); NOTE: Duolingo has a lot of examples of "dejar de" in their program. ocuparse de (to forget to); tratar de (to try to) EXAMPLES Julio acaba de llegar. Julio just arrived. Me algro de hablarle. (I am glad to talk to you.) This is using the formal you, of course. Me canso de esperar el tren. (I am getting tired of waiting for the train.) DE has many, many uses en español, but you asked about its connections to verbs. Gracias a Barron's Spanish Grammar, 2nd ed., Christopher Kendris.
"Con" means "With" "Un/Una" means "A/An" "De" can mean "to" or "of" or "about", depending on the sentence. It's a very common preposition that is used in almost all existing contexts.
"El auto de mi padre" (My father's car)
"Salir de casa" (To leave home)
"Hablaba de ti" (I was talking about you)
This is what confuses me about when to add those little words that, to me, seem repetitive. Comprender already means 'to understand' or 'to comprehend'. Adding another word before that seems like you'd be saying "This is impossible to to comprehend." Sometimes the extra words are left off and sometimes they aren't. I can't totally figure out the rule on this.