Ty to sing more English songs , and you will find it interesting _______ a foreigh language.
We want to be ______ because, as students, we should learn to help other people.
I am too busy to listen to her ______ talking. She has talked for about two hours.
-Look, your sister is playing the piano over there.-She ______ be my sister. She has gone to America.
It is polite ______ you to give seats to the elderly.
-Why are there a lot of dead fish in the river?-Because they were ______ by the polluted water.