The experiment, though they had tried their best, ________ to be a failure.
What _______ the doctors most was that they could not find the cause of the strange disease.
It is ________ that Arthur gave back the money he found.
They have ______ a plan for reducing the budget deficit(财政赤字), which is quite practical.
I waved to Nancy, but she was _______ in her thought, and made no response.
With ______ help of his teachers, he made ______ great progress in his study.