Answers B and D
Explained:
If you just memorize a list of words and you don't understand any meanings then their is no point in knowing the work, though you may know the word and now you can use it, you wouldn't be able to use it right because you would use it incorrectlyIf you.
Answer D is merely a statement. Though it may be a true statement this would be advise someone gives making it a non-answer
c. us should polish each part
C as it has a better view on the situation