I__was paying___ for my things when I _heard___ someone call my name.
I ___turned__ round and __saw___ Paula
She ___wore__ a bright red coat yesterday.
We ___stopped__ to have a cup of coffee. 
23. While we __was having___ a drink, a waiter __dropped___ a pile of plates. 
24. We all __had___ a terrible shock. 
25. While the waiter _was picking____ up the broken plates, he _cut____ his finger. 

Đây là một đoạn văn liền mạch đó bạn, đừng tách câu ra chứ, mãi tui mới luận ra đc đó