When Helen saw her tutor nod ______ to her, she calmed down and went on with her performance .

-Are you familiar _______ the music? -Yes. The music is familiar __________me,but I can`t remember when and where I heard.

—You don’t see the professor from Singapore quite often, do you? —No, we only meet ______．

The attempt and insistence on purchasing the Diaoyu Islands by Japan will ______ harm    China-Japan ties．

It has been proved that taking exercise ________ does good to one’s health.