Unprecedented means something that has never happened before. Some people may use the word as something they've never seen before, but it really means something that has never been preceded by the same thing.
The home run record set by Barry Bonds is unprecedented.
i do not know how to use embalming in a sentence. (there is the sentence)
So- you are asking when to use 'when' in a sentence. When you are asking how to use when in a question, you are already using when in a sentence, because a question actually is a sentence. I like to use when in a sentence whenever I like.
How do you use sedition in a sentence
use contingency in a sentence?
use adainty as sentence
use aver in a sentence
Can you use abstemious in a sentence?
use ize in sentence
This is how you use mound in a sentence
enjoin use in sentence
how can we use travelogue in the sentence
Use it in a big sentence.