In the last ten years, they _______ three great scientific experiments.
---What did the Englishman say? ---Oh, he asked where ____ .
The number of the students in our school ____ rising since 2006.
Helen has had a lot of trouble these days,but she doesn’t know whom to ______ for help.
I have been teaching for over twenty years, but never _____ a girl as bright as Lily.
I _____thank you too much for all your help to my son while we were away from home.