Rana: I want a puppy. because it's cute.
Correct: I want a puppy. Because it's cute.
Explanation: After the period on the sentence, you start the next sentence with a capital
letter.

Also, The words, and, but, so and because are examples of
conjunctions. These are words that connect similar kinds of words or group
of words to help achieve a single idea. It is right to begin a word with a
conjunction, but it would be more formal to complete the sentence with it.

Therefore, in your sentence, you may write it like this: I want a puppy because it's
cute.

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Hello, Rana! Thank you for passing your homework! You did the sentences well! I just
explained some minor corrections. Also, don't forget to write a period after your sentences. That's all, Rana! See you in class!