Jack, to his _______, refused to get involved although his friends insisted on his trying the drug.
The novels written by the author sell best, but five years ago no one could have imagined how great a role he________in the literary world.
He turned down the request of his friend because it was________the limit of his power.
If you had worked hard, you ______ so anxious now.
______ I'm willing to help, I do not have much time available.
The rise of oil prices made scientists search for new energy resources ______ oil.