As a boy, he was_______ hard all day long.
The area ______ the explosion happened was closed off by the police.
She had a bad cold, but luckily began to _______ soon.
Everyone was trying to ________ a better idea to persuade him to stay.
Use your head, _______ you’ll work out the problem.
_______ is known to all, Lu Xun was famous as a great thinker.