7.
Your Answer is
Correct Answer is A
Explanation
Note that although this associative adverb is placed inside the sentence, it also indicates the relationship between the previous complete sentence and this sentence, so it should be placed at the beginning of the sentence to make it easier to read. The preceding sentence indicates a mouthful of lyrics that needs more practice. The latter sentence indicates that the greater challenge is to learn to breathe, so the relationship between the front and the back is a turning point, and A is correct.