By law,when one makes a large purchase, he should have _____ opportunity to change his mind.

 When it comes to the civil war in Syria, the US government’s attitude towards it has experienced a(n)_______ change , which may have a positive effect on Syria present situation.

Eric, a middle-aged fashion designer, is very happy because the clothes be designed have never been ________.

Can you tell the ________ difference between the words “require” and “request”? I sometimes get puzzled by their meanings.

The passer-by jumped into the cold water to save the _____ boy, who cried for help, but it was too late and the boy was _______ at last.