I want to learn how to play cello!
It looks really cool and fantastic!
And I also like to play instruments!
It will be expensive and hard to learn cello, but I want to try it someday!
I tried violin, so it will be easier than learning other new instrument!

“For all things I have the strength through the one who gives me power.” —Philippians 4:13
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I want to learn how to play the cello!
It looks really cool and fantastic!
And I also like to play instruments!
It will be expensive and hard to learn the cello, but I want to try it someday!
I tried the violin, so it will be easier than learning another new instrument!

= We put the if we are talking about a specific instrument. 
= We use another or the other if there is one thing. 
= Overall, your sentences are fantastic! :)