Sam________some knowledge of the computer just by watching others working on it.
Mr. Smith is busy these days ________ a new book on how to develop a child’s reading skill.
It makes no ________ to me what she says. I won’t care.
Who do you think is the right person to ________ the task?
He transplanted the young tree to the park ____it was the best time for it .
—It is a lovely day ,isn`t it ? — yes,______?