The selfless village doctor treated whoever came to his family without any_   _.

“Tommy, run! Be quick! The house is on fire!” the mother shouted, with ________ clearly in her voice.

We will be given a(n)        to ask questions at the end of the lecture.

Classification is a useful ______ to the organization of knowledge in any field.

Radar enables the pilot of an airliner to take off, fly and land in _____.