n. the condition of being essential or indispensable
n. anything indispensable
n. 需要, 必需品, 必然
[法] 必要性, 必然性, 必要
1. Water is a necessity for all living beings.
水是所有生物的必需品。
2. In modern life, a smartphone has become a necessity for communication.
在现代生活中，智能手机已成为沟通的必需品。
3. It is a necessity to wear a seatbelt while driving for safety.
开车时系安全带是出于安全的必要。