31. New York City is busier than any other city in the world.
C. New York City is the busiest city in the world.
32. He is too short to play basketball.
A. If he were not short, he could play basketball.
33. COVID-19 vaccines/invent/help/fight/pandemic.
C. COVID-19 vaccines were invented to help fight the pandemic.
34. She/not/play/piano/five years.
A. She hasn't played the piano for five years.
35. it/ rain / heavily,/singers/ still / performed / stage.
C. Although it rained heavily, the singers still performed on stage.
36. When is Earth Hour?
B. at the end of March every year
37. What do people do for Earth Hour?
A. Switch off non-essential lights.