Formal language is also called "proper language" because it is the type of language you would use when first meeting someone or giving a speech at a high class place so the correct answer is:
<span>B) Have I convinced you that the study of grammar is important and well worth your effort? </span>
The sentence which uses correct punctuation is C. In time, of course, all issues get resolved, but not necessarily in the way you would like.
In A, the comma before <em>he was concerned </em>should be a dash. In B, there should be a colon before <em>a flashlight, </em>not a semi colon. In D, there should be a comma before <em>yet, </em>and not a colon.
She is as quiet as a mouse, so she barely speaks or makes noise.
I personally think it’s : A prefix is placed before the root of a word; a suffix is placed at the end of the root ... hope This helps
