The old man _____live with his wife, but now he ______alone after she died.
--Mr. Lee__________to a student when I entered the classroom this morning.---He is very patient________ he is young.
After running a 1000-metre race, he was________.
The country life he was used to ____ greatly since 1992.
In our school library there_______ a number of books on science, and in these years the number of them_______ growing larger and larger.
The rivers will become dirtier and dirtier________ we take action to protect them.