-------He says that my new car is a ____________ of money.  -------Don’t you think those words are just sour grapes? 

I can’t say which wine is best—it’s a（n） _______ of personal taste.

When a difficulty is beyond my _____, I turn to my classmates or teachers for help.

I listened to Dr．Wilson's lecture about the protection of wild animals, but I was unable to grasp its key     .

The students union was founded for the______ of them.