When I saw the cleaner, he _____ the meeting room.

• When/ While দ্বারা যুক্ত দুটি Clause এর একটি যদি ast Indefinite tense হয় তবে অন্য clause টি Past Continuous হবে।
Example: When you called, I was in a meeting.

→ আবার When/ While এর পর পরই যদি Verb থাকে তার সাথে ing যোগ হবে।
- কিন্তু When/ While এর পরে Subject থাকলে When/ While এর অংশটি Past continuous Tense এ হবে।
যেমন:
→ While (walk) in the garden, a snake bit him.
- While walking in the garden, a snake bit him.
→ When he (walk) in the garden, a snake bit him.
- When he was walking in the garden, a snake bit him.

• সুতরাং এখানে When I saw the cleaner, he was cleaning the meeting room হবে সঠিক উত্তর।

Source: Advanced Learner's Grammar & Composition by Chowdhury & Hossain.