It was on October 3, 2011 _____ a big fire happened in Beijing, _____ was a great shock to lots of people.
When you________, use a handkerchief to cover your nose and mouth. This is particularly necessary in public places.
Pictures on TV show the quake-hit capital________to ruins and helpless survivors waiting eagerly for relief.
Having worked as a doctor for so many years, Mr. White has________rich experience in battling with various diseases.
A trip to the forest park is a wonderful________of my happy childhood, when I had no end of fun with my playmates.
I must have been a great_________to my parents in those hard days, for I never failed to live up to their expectations.