The instructor really knows the subject.
The sentence is referring to a instructor so it should be the instructor not that instructor. It shouldn't be written as reallyknows it should be really knows. There is no need to capitalise the first alphabet of subject as it is simply a common noun.
To know more about "grammar and editing" refer to the link here:brainly.com/question/49114646
Answer:
A. when sending an invitation
Explanation:
The correct answer is A. when sending an invitation; when sending an invitation, it would be a personal letter because personal information can be embedded in the letter.
The other options B, C, D are formal letter. You wouldn't send anything personal when providing information about services OR when answering ad for a job OR when asking a company for information.
