1.    The professor gave only a brief (allusion illusion delusion) to the work at hand. 

2.    Jane's sweet smile is only a/an (allusion illusion delusion).

3.    Daniel gave a slight (allusion illusion delusion)  to his history as a police officer at the beginning of the date.

4.    I've found that believing in love is nothing more than  a sad (allusion illusion delusion).

5.    Ryan doesn't like you.  You believe in a/an (allusion illusion delusion).

6.    He didn't actually come out and say so.  It was only an (allusion illusion delusion).

7.    That image isn't real.  It's only a/an (allusion illusion delusion).

8.    The best (allusion illusion delusion) is a close-held belief.

9.    The author gave a small (allusion illusion delusion) to her personal life.

10.    My trust in religion is not a/an (allusion illusion delusion).