is known to us all is the old scientist, for whom life was hard in the past, still works very hard in his eighties.
Scientists say it may be five or ten years___________ it is possible to test this medicine on human patients.
My uncle___________ until he was forty-five.
--What when I phoned you?
Sometimes words alone were not enough to _________pupils along the path of knowledge
. Neither of them knew what was doing.