A boy is riding a bicycle happily down the street.
Or
The girl is riding her bicycle to the park.
These sentences show present action using “is” with an action word ending in “-ing” as per the correct format.
Class 4 English Santoor Grade 4 Chapter 4 One Thing at a Time question answer
Class 4 NCERT English Santoor Chapter 4 One Thing at a Time solutions
Here is a sentence using the format “is/are + action word + ing”:
“The boy is riding his bicycle quickly towards the playground.”
This sentence describes an action happening right now. If there were two people, we would say, “The boys are riding their bicycles.” The word “is” is used for one person, and “are” is used for more than one. Adding “-ing” to the action word makes it clear that the activity is happening at this moment.
For more NCERT Solutions for Class 4 English Santoor Chapter 4 One Thing at a Time Extra Questions & Answer:
https://www.tiwariacademy.com/ncert-solutions/class-4/english/