Hey there! So diction basically means what words that the author uses. If they use certain words together, it can create the mood, which in this case is unease. An example might be using words like, "dark", "shadow", "creaking", "silence", or "creepy" in a horror/ scary story. When used together in the story, it can create the mood that something bad migjt happen. The author choses these words carefully to fit the passage. In otherwords, he would not use happy words if writing a horror story.
        
             
        
        
        
Answer:
2. A. would have to take
3. B. is
4. D. ought to
5. C. needn't have done
6. A. should send
7.  C. is to, will have
8. B. mustn't
9. C. ought
10. C. can be done
11. B. will be able
12. C. might be
Explanation:
I have been able to fill the empty spaces with the correct answers.
We see the use of modal verbs in the sentences. Modal verbs are known to be auxiliary verbs that actually express the mood of another verb. These modal verbs are actually used to show possibility, speculation, deduction, prediction, etc. 
 
        
             
        
        
        
You need to make a clear distinction:)