B. Put in articles where necessary. 1. What is ... difference betweenopera and ... operetta?2. English is ... global language nowadays. 3. What ... interestingperiodicals! 4. Indian elephant is ... endangered animal. 5. Will ...mystery of Loch Ness Monster be ever discovered? 6. Each child got... sweet. 7. Put on ... clean shirt, Alec! 8. ... sun is shining sobrightly, but there are ... clouds in ... sky. 9. - Where are pota-toes I bought yesterday? I put them in ... fridge. 10. Have youdone exercises yet, Mary?​

I was walking along the street when I heard a cry.
I wasn't walking along the street when I heard a cry.
What was I doing when I heard a cry?
Was I walking along the street when I heard a cry?

He was driving too fast when the crash happened.
He wasn't driving too fast when the crash happened.
How was he driving when the crash happened?
Was he driving too fast when the crash happened?

When the train left the station she was still standing on the platform.
She wasn't standing on the platform when the train left the station.
Where was she standing when the train left the station?
Was she still standing on the platform when the train left the station?