The essential use case does not make these references.

基本用例不引用它们。

youdao

Comparing a system use case and an essential use case.

比较系统用例和基本用例。

youdao

The system use case has more steps than the essential use case.

系统用例的步骤比基本用例的步骤多。

youdao

But the legislation is not to everyone's liking. John VandeBerg, director of the Southwest National Primate Research Center in San Antonio,Texas, says the use of chimpanzees in biomedical research is essential.

VOA: standard.2010.02.16

When temperatures are this extreme several days in a row, power companies scramble to manage peak demand, often urging consumers to turn off non-essential use of electricity.

WHITEHOUSE: Energy and Environment Latest News | The White House

The current drought has forced disaster declarations in 26 states and a spate of emergency conservation orders, including in Warrenton, where the city ordered residents to stop watering their lawns, shut down commercial car washes and banned and just about every other non-essential use of water.

CNN: U.S. drought biggest since 1956, climate agency says

"The issue is starting to be recognized as a legitimate object of clinical attention, as well as an economic problem, given that a great deal of non-essential internet use takes place at work, " said Dr Aboujaoude.

BBC: NEWS | Technology | US shows signs of net addiction