Before the final examination, many students have shown ____ of tension. Some have trouble in sleeping while others have lost their appetite.

Professor Li, do you like Ewa and can you make a(n)_______ on her new movie?

Peter is a brilliant language leaner. Within two weeks, he has developed a good _______ of Chinese and Japanese. 

He is an old doctor with a lot of ________. But he has never travelled by air before.Taking a plane was quite ________ experience for him this time.

The students union was founded for the______ of them.