The old lady hurried to the station, only ________ Lei Feng had left.
My sister is _______ about what she eats, otherwise she would not be so thin.
I know a little bit about the city as I __________ there for one year in my youth.
While working in the countryside, the students a great deal of knowledge on plant life.
Criticism and self-criticism _____ necessary _____ it helps us to correct mistakes.
Running a company is not _______ a matter of hiring people — they also need to be trained.