It is so noisy in the restaurant and hard for us to ________ a conversation.
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.