The government placed _____ on the numbers of foreign cars that could be imported.

The police are trying to find out the ________ of the man killed in the traffic accident.

Many people like white color as it is a ________ of purity.

— Why does he never pick up the waste paper on the ground?— Maybe because he thinks it’s beneath his         to do so．

Most graduates in big cities are suffering form       connected to soaring house prices and job hunting.