21. Everything comes with price; there is no such thing as free lunch in the world.
A. a, a B. the, / C. the, a D. a, /
22. Lucy has a great sense of humor and always keeps her colleagues with her stories.
A. amused B. amusing C. to amuse D. to be amused
23．I had great difficulty the suitable food on the menu in that restaurant.
A. find B. found C. to find D. finding
