Do you know where the headmaster is? I have something urgent. — Oh, he ____ have gone far, for the computer is still on in the office.[ ]

My uncle _________ drive a car two yearsago. Now he drives very well.

　　　　is no doubt 　　　　Bob can win the first prize in the match.

doesyour sister practice singing English songs —-Twice a week.

He directed exposure to pigs,otherwise he_______pig flu.