How do I iterate over a Split<&Str>

Hi, I got stuck while working on my first project in Rust

My code:

    let mut index = 0;
    for i in l_a {
        let  sne = i.split(" ");
        for a in sne {
            print!("{} ",m[index]);
            index+=1;
            if a == sne[0] {
                print!("\n")
            }
        }
    }

So right here I am splitting a string but I want to check if a the iterator is the last value of sne the splitted string but it gives me an error:

error[E0608]: cannot index into a value of type `std::str::Split<'_, &str>`

Kindly help me
This project means very much to me
In case you want the full code there is a github gist below

You might want to do something like this, with the Iterator::enumerate method. This will print a newline after the first word in each line:

        for (pos, a) in sne.enumerate() {
            print!("{} ",m[index]);
            index+=1;
            if pos == 0 {
                print!("\n")
            }
        }

index 0 is the first element, not the last element. If you want to print a newline after the last word in each line, you can put a print! statement after the loop instead:

        for a in sne {
            print!("{} ",m[index]);
            index+=1;
        }
        print!("\n")

By the way, it looks like you could simplify this program by doing the work in a single loop, instead of two separate loops:

fn main() {
    let stop_words = ["but","has","the", "is", "a", "an", "they", "and", "I", "in", "there", "was", "who", "The", "know", "it"];
    let file = std::fs::read_to_string("src/Text.txt").expect("Couldn't read file");
    
    for line in file.lines() {
        for word in line.split(" ") {
            if stop_words.contains(&word) {
                print!("{} ", word.to_lowercase());
            } else {
                print!("{} ", word.to_uppercase());
            }
        }
        print!("\n");
    }
}

Thanks @mbrubeck , but you know the solution would be same and I am really proud of what I made and i also fixed the issue by creating another vector and having all the case sensitive words in it and to print new line I just did (vector name = ls)

if a == ls[ls.len() - 1] { print!("\n") }

And Thanks Again
But If you like you could reply on another topic like this to help me out
And on that topic I am just asking you to give me ideas for projects that would help me make myself comfortable with rust.