Han Mei often practices English.
—Ann has finished her homework, hasn’t she?—Yes. She _____ it an hour ago.
—Is your brother at home?—No. He ________ the library. He hasn’t come back yet.
We know that about seventy percent _____ the earth _____ covered by water.
you drive, you will be.
The policeman asked the child ________ cross the street ________ the traffic lights turned green.