Question 15: If you don’t know how to spell a word, you_____ look it up in the dictionary.
With the exception of the first conditional, the following structural clause can be used to give advice, or can to express possibility. We choose C
Answer D is wrong because it must be ought to
Answer A does not match the semantics of the sentence
Answer B could not complete the sentence with correct grammatical structure
Translation If you don’t know how to spell a word, you should look it up in the dictionary