The mountains form a natural            between the two countries so they have no trade relations in history.

Please don’t ask me to solve mathematical problems; they are beyond my ____.

The League member is brave, honest and hard-working. In a word, he is a good boy of many _____. 

. You must be there within an hour. There should be no _______ in sending the information. 

The man has gained an evil reputation. That’s to say he has a bad _____.