_____ is known to us all is that America is a developed country _____ the First World.
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.