22.Lawrence Craven, a doctor from the USA,is the author of several published reports, one of______ introduced the idea in 1953 ______aspirin could reduce the risk of heart attacks.
Tony ______ his homework this morning before he went to school.
He was about to tell me the secret _______ someone patted him on the shoulder.
E-mail, as well as telephones, _____ an important part in daily communication.
Hiking is ______ great fun. You will get close to ______ nature and take exercise at the same time.
Police have not_______ the possibility ______ the boy was take by aliens .