countless means numberless, so it can be used as:
"He had countless posters of Jonas brothers in his room"
the girl was countless the girl was countless
there are countless possibilities to the question that you just asked.
A sentence using countless:Isn't it amazing how the countless stars scatter the dark sky?
Last summer was intolerably hot so we spent countless hours in the pool.
There have been countless time that i have forgotten my lunch.
Example: I cannot remember the countless times I had told you to take a shower.
Countless disagreements over the proper use of national forests have engendered feelings of hostility between ranchers and environmentalists.
Her mom told her countless times to wash the dishes.(Note: Most sentences would contain "countless times".)
Throughout the world's history, there has been countless of murders and deaths.
You can use the word Truss in a sentence like this.
Can you use the word concluding in a sentence? Done.
Just use it! Or do you mean, can you use the word beheld in a sentence.