My parents as well as my sister _________playing table tennis .
They really don’t know how _________ the difficult problem.
They used to be friends, ______?
It has been many years ________ we met at the train station in 2008.
--How can young people realize their dreams? --No matter what difficulties they meet, they can’t ________.
Basketball ________ by a Canadian doctor ________ James Naismith.