Those black clouds are a sure _____ that it’s going to rain. 

There were so many cars held up by the heavy rain on the road that we had no        but to wait.

Ladies and gentlemen, please raise your glasses and drink a _______ to the success of the new company.

The lion is considered the king of the forest as it is a（n）______of courage and power.

 —Excuse me, may I ask you some questions? ---Sorry, I’m too busy and haven’t even a minute to________.