Mr. Zhang has retired already. He in our school for over thirty years.
. The government has to close those small factories to prevent the water of the river ______.
If you keep on, you will succeed ________.
—________ you__________ the editor at the airport? —No, when we got there, he___________ driven away.
Does the way you thought of___________ water clean make any sense?
—What do you think of his opinion?—None has given me ___________ piece of advice.