I______ thank you too much for all your help to my son while we were away from home.
—Who ________ it be that is knocking at the door? —It________ be Mother, but I’m not sure.
If you cheat in the exam, you could hardly________ it.
He once studied in Zhejiang University, ________he went abroad for further study.
More attention should be paid __________ English.
More than 60 million people in southwestern China ________the drought nowadays as a result of less rainfall, environmental damage and so on