What's going on?
Insight: The sentence describes an action happening right now, so we need the present continuous tense.
Choosing the right verb form:
- The sentence is about Sasha doing something at the moment.
- The present continuous tense is formed with 'is/am/are' + verb-ing.
- Since Sasha is a singular subject, we use 'is'.
- The verb needs to be in its -ing form, which is 'doing'.
Let's put it together:
Sasha is doing his homework now.
Answer: is doing