The newly developed science of artificial intelligence aims at programming the computer to think，reason and react （ ）people do.
He should（ ）what he's good at, and not switch to something he knows nothing about.
The theory of（ ）was developed by Darwin and is now understood by nearly everybody in the world.
People tend to ignore the delayed effects of（ ）to chemicals because the danger doesn't become apparent immediately.
It is rude to（ ）when two persons are holding a conversation.
The farm ministers scheduled an emergency meeting in Luxembourg in hopes of easing the worldwide "mad cow"（ ）.
