When Helen saw her tutor nod _______ to her, she calmed down and went on with her performance.
The two sportsmen congratulated each other _______ winning the match by shaking hands.
Information has been put forward _______ more middle school graduates will be admitted into universities.
She stepped on my foot _______, not _______, which made me angry.
He had to _______ paying the bills because of a lack of money.
When she saw her son liked reading, she did all she could ______ him.