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.
They said they ______ do some sports if it was fine.
He ______ in Shanghai University for four years before he ______ Beijing.
Mary said it was at least five years since he ______ a good drink.
Xiao Pei said she ______ Hainan for 3 months.
--What are Mr and Mrs Black doing ? ---They _____ tea in the garden.